Calendula

Few botanical ingredients are as closely associated with the idea of healing as calendula. For centuries its unmistakable orange and golden flowers have been infused into oils, incorporated into ointments and applied to skin that is dry, irritated or damaged. Today calendula appears in everything from traditional herbal salves to sophisticated cosmetic formulations intended for sensitive skin, and it is frequently described simply as a healing herb. The science requires considerably more nuance.

At a glance

Calendula: the reputation of a healing flower

Some botanicals are defined by fragrance. Lavender is almost impossible to separate from its aroma, rose has become inseparable from perfumery, and peppermint announces itself through menthol before its botanical identity is even considered. Calendula is different. Its reputation has been built principally around what people believed it did. For generations, the brilliant yellow and orange flower heads of Calendula officinalis have been harvested and transformed into preparations intended for uncomfortable or damaged skin, and that association has proved remarkably durable. Search for calendula today and the vocabulary remains familiar: soothing, calming, repairing, regenerating, healing.

These words sound reassuring. Scientifically, however, they describe very different things. A formulation may feel soothing without altering inflammation at a cellular level. An ingredient may demonstrate anti-inflammatory activity in cultured cells without producing a meaningful improvement in human dermatitis. An extract may accelerate aspects of wound closure in an experimental animal without becoming an appropriate treatment for wounds in people. And an ingredient associated historically with wound care cannot automatically be described as a clinically proven wound-healing agent.

These distinctions matter. Calendula deserves neither unquestioning enthusiasm nor casual dismissal. Its long history has generated legitimate scientific questions, and modern research has produced plausible biological mechanisms worthy of further investigation. The purpose of this monograph is therefore not to decide whether calendula works, because that question is too simplistic. Instead we ask something more useful: what exactly is calendula, what does it contain, what has it traditionally been used for, what biological effects have researchers observed, and how confidently can those observations be translated into modern skincare? The answer begins with the flower itself.

Botanical identity

Common names are wonderfully convenient and notoriously unreliable, and calendula provides a perfect example. Calendula officinalis is commonly known as the pot marigold, and for generations it has also simply been called marigold, yet many of the brightly coloured flowers sold today as garden marigolds belong to an entirely different genus, Tagetes. French marigolds, Tagetes patula, and African marigolds, Tagetes erecta, are not calendula. They belong to the same enormous botanical family, Asteraceae, but represent distinct genera with different chemistry and different histories of use. This distinction becomes particularly important when discussing skincare, because a historical reference to marigold, a bottle labelled marigold extract and a modern cosmetic ingredient identified as Calendula officinalis cannot automatically be assumed to describe precisely the same botanical material. Throughout this monograph, calendula refers specifically to Calendula officinalis L., a name formally published by Carl Linnaeus in Species Plantarum in 1753 and still recognised as accepted by modern botanical authorities.

A composite flower within the Asteraceae

Calendula belongs to Asteraceae, sometimes historically called Compositae, a family containing tens of thousands of species including daisies, sunflowers, chamomile, echinacea, arnica, dandelions, chicory and artichokes. What looks like a single calendula flower is actually an entire inflorescence composed of numerous individual florets arranged together into a compact head, an evolutionary innovation that presents many tiny flowers together as one highly visible target for pollinators rather than requiring an insect to locate them scattered across the plant. The outer structures commonly mistaken for petals are ray florets, forming the conspicuous yellow or orange perimeter, while numerous smaller disc florets sit toward the centre. Commercial ingredients specifying Calendula officinalis flower extract may therefore vary in chemical composition depending upon the proportions of floral tissue present, cultivar, maturity and processing, and the rich yellow and orange pigments responsible for much of that variation arise largely from carotenoid compounds accumulated within the floral tissue.

Calendula is generally cultivated as an annual, although under suitable conditions it may behave as a biennial or persist longer than expected, forming branching herbaceous growth with somewhat sticky or glandular leaves and flowers ranging from pale yellow through golden yellow to deep orange. Modern horticultural selection has produced numerous cultivars differing in flower colour, size, number of ray florets, growth habit and flowering duration, and while these differences are principally aesthetic for the ornamental gardener, cultivar can potentially influence yield and phytochemical composition for producers interested in botanical extracts. A deep orange flower and a pale yellow flower may both belong to Calendula officinalis, yet differences in pigmentation can reflect differences in the concentration and proportions of carotenoid compounds, and as with lavender, botanical identity is only the beginning of ingredient identity.

Native range and the meaning of its name

Calendula has been cultivated for so long, and has escaped from gardens so successfully, that determining its original geographical distribution has historically proved surprisingly difficult. Modern taxonomic sources place the native range of Calendula officinalis in the western Mediterranean, from where human cultivation has since carried it across much of Europe and into numerous temperate and subtropical regions. Its success as a cultivated plant is easy to understand: calendula germinates readily, flowers generously, tolerates a range of garden conditions, and can be harvested repeatedly over a long flowering season. One proposed explanation for the genus name connects it with the Latin calendae, the first day of the month, commonly interpreted as a reference to that unusually long flowering season, though as with many botanical etymologies the story is often repeated more confidently than the historical evidence warrants. Regular harvesting or deadheading encourages continued production, and for historical households that persistent availability, rather than one brief annual harvest requiring careful preservation, may have contributed substantially to calendula’s long relationship with domestic medicine.

The second part of calendula’s scientific name is equally revealing. The epithet officinalis appears repeatedly among plants with long histories of medicinal, culinary or apothecary use, connected with the Latin officina, the working room or storeroom associated with monasteries and later apothecaries in which medicinal preparations were kept and prepared. An officinal plant was therefore one recognised within established medicinal or apothecary practice. This does not mean the word officinalis provides evidence that a plant is medically effective, since botanical nomenclature is not a clinical trial, but the name acts almost like a historical fingerprint: it tells us that when calendula received its formal scientific identity, its relationship with practical herbal use was already deeply established.

Why botanical identity matters

Calendula’s brilliant colour and composite flower structure exist for reasons that have nothing to do with human skincare, having evolved within relationships involving pollinators and reproductive success, and humans subsequently selected the plant for even larger, brighter and more elaborate flowers. Calendula’s membership of Asteraceae also places it within the same family as chamomile, another botanical strongly associated with soothing skincare, but that relationship should not be overinterpreted. Plants belonging to the same family may share structural and evolutionary characteristics without possessing identical chemistry, and calendula and chamomile cannot be substituted for one another simply because both belong to Asteraceae or share histories of traditional use for irritated skin.

This illustrates a principle that runs throughout the Botanicals and Company Ingredient Library: the phrase plant extract is rarely sufficient information. Before interpreting research or evaluating a cosmetic ingredient, we need to know which species was used, which part of the plant was harvested, where and how it was cultivated, when it was harvested, how the material was dried, which extraction solvent was employed, the ratio of plant material to solvent, whether the extract was standardised, how it was stored, and how much was incorporated into the final formulation. A clinical study investigating a hydroalcoholic calendula extract cannot automatically validate a cosmetic containing a minute quantity of calendula-infused oil. Both may legitimately contain Calendula officinalis. Chemically, they may be very different ingredients, a distinction that becomes particularly important when we examine the evidence for wound repair later in this monograph.

History and traditional uses

Calendula’s history is not dominated by royalty, exploration or luxury, and that may be precisely what makes it interesting. For much of its relationship with people, calendula belonged to the practical garden: colourful enough to be ornamental, useful enough to be harvested, sufficiently uncomplicated to cultivate and versatile enough to find its way into food and household preparations. Rather than occupying one clearly defined role, calendula moved easily between them, as a flower, a food colourant, a garden herb, an ingredient in household preparations and eventually an established medicinal plant, and that ability to exist simultaneously in the kitchen, garden and apothecary helped it persist through enormous changes in European life.

The deeper history of calendula is difficult to reconstruct with precision. Plants now identified as Calendula officinalis belong to a genus centred strongly around the Mediterranean and surrounding regions, but historical botanical texts frequently used plant names that do not correspond neatly with modern taxonomy, making retrospective identification difficult. A medieval author might describe a plant using a vernacular name shared by several species, illustrations may be stylised, descriptions may have been copied from earlier works rather than made from living specimens, and plants may have changed in appearance through centuries of cultivation. Consequently, claims that a specific ancient civilisation used precisely Calendula officinalis for a particular medical purpose should be approached carefully unless botanical identification can be established. What can be said with considerably greater confidence is that calendula became deeply embedded within European herbal and domestic traditions.

One of calendula’s most practical historical uses had nothing to do with skin. Its brightly coloured petals could be incorporated into food, used to add colour to preparations including broths, butter and cheese, and calendula acquired a reputation as an inexpensive substitute for the far more costly saffron, giving rise to one of its familiar historical descriptions, poor man’s saffron. The comparison should not be interpreted chemically, since calendula’s carotenoids and saffron’s crocins are different compound families producing a superficially similar colour rather than an equivalent flavour or chemistry, but the nickname captures something true about calendula’s place in the household: it was accessible where saffron was not.

Alongside that culinary role, calendula developed another enduring identity as an ingredient prepared specifically for the skin. Flowers were infused into fats or oils to create golden preparations later incorporated into salves and ointments, while other preparations used water or alcohol to extract different components of the plant. As European herbal traditions became increasingly documented, calendula appeared repeatedly in herbals and pharmacopoeial practice, its reputation becoming particularly associated with cuts, chafing, minor burns, inflamed or irritated skin and slowly healing wounds. These historical uses should not be confused with modern clinical evidence, since earlier herbalists worked without controlled trials, microbiology or an understanding of cellular wound repair, but the consistency of calendula’s association with damaged skin across generations is striking, and that consistency is part of what modern research set out to examine.

Ingredient forms

There is no single cosmetic ingredient called simply calendula. The word describes a species, not a raw material, and the way that species is processed determines what a formulator or consumer actually receives.

Dried flower. The starting material for most calendula preparations is the dried flower head, generally described in pharmacopoeial sources as the whole or cut, dried, fully opened flowers of cultivated, double-flowered varieties. Dried flowers may be used whole in infusions and compresses, or powdered for incorporation into cosmetic bases, and quality depends heavily upon the proportion of ray florets to other floral tissue, since much of the pigment and phytochemical interest concentrates in the petal-like ray florets.

Oil macerate. Perhaps the most familiar calendula cosmetic ingredient is an infused or macerated oil, produced by placing dried flowers into a vegetable oil and allowing lipid-soluble compounds to migrate from the plant material into the carrier over a defined period, sometimes under controlled temperature to improve reproducibility. This is not calendula oil in the sense that lavender essential oil is a distilled aromatic material; calendula does not produce a comparable commercial essential oil, and a macerate is fundamentally a carrier oil containing an extracted fraction of calendula constituents, meaning the identity of the carrier, whether sunflower, olive, soybean or sweet almond oil, is genuinely part of the finished ingredient.

Aqueous and hydroalcoholic extracts. Calendula may also be extracted into water, glycerine or water and alcohol systems, capturing a different chemical spectrum from an oil macerate. More polar compounds, including certain flavonoids and phenolic constituents, may be represented quite differently depending upon the extraction solvent, making these preparations particularly useful in emulsions, gels, cleansers and toners containing an aqueous phase.

Tinctures. A tincture, typically an ethanolic or hydroethanolic extract, concentrates a broad range of constituents and has a long history in both traditional herbal medicine and cosmetic formulation, though its alcohol content and sensory profile suit it to particular product types rather than universal use.

CO2 extracts. Carbon dioxide extraction offers another route to concentrating selected lipophilic constituents under controlled pressure and temperature, before the carbon dioxide is removed from the finished material. Such extracts may offer advantages in concentration and solvent residue compared with some conventional methods, but their composition depends heavily upon extraction parameters, and they should be treated as distinct ingredients rather than concentrated versions of every other calendula preparation.

Whichever form is chosen, the underlying lesson is the same one that runs throughout this monograph. Extraction determines composition, and a formulator wishing to reproduce or investigate a particular calendula effect must select a raw material actually capable of delivering the relevant constituents, rather than assuming that the word calendula on a supplier’s data sheet is sufficient information.

Chemistry

The reputation of Calendula officinalis as a plant associated with irritated and damaged skin developed centuries before anyone could identify the molecules contained within its flowers. Modern phytochemistry has transformed that picture. Calendula flowers contain a chemically diverse collection of secondary metabolites, including triterpenoids, flavonoids, carotenoids, phenolic compounds, polysaccharides, sterols, saponins and smaller quantities of volatile constituents, and this complexity matters, because there is no single molecule that can reasonably be described as the active ingredient responsible for everything attributed to calendula. Different preparations extract different fractions of the plant, and those fractions may behave quite differently: a calendula oil macerate is not chemically equivalent to a hydroalcoholic extract, an aqueous infusion is not equivalent to either, and even two extracts bearing the same botanical name may differ according to cultivar, growing conditions, flower maturity, extraction solvent, temperature, extraction time and subsequent processing.

Triterpenoids and faradiol

Among the most scientifically interesting constituents of calendula flowers are the triterpenoids, a large and structurally diverse family of plant secondary metabolites occurring throughout the plant kingdom. Calendula contains several triterpene alcohols and their fatty-acid esters, and particular attention has been given to compounds associated with faradiol, together with related triterpenoids including arnidiol, calenduladiol and derivatives of taraxasterol. Faradiol is a pentacyclic triterpene diol occurring within calendula flowers, also present as fatty-acid esters including derivatives of lauric, myristic and palmitic acids, and a widely cited study isolating faradiol esters from calendula flowers reported anti-oedematous activity comparable in molar terms to indomethacin in an experimental model of inflammation. This does not mean faradiol is a pharmaceutical anti-inflammatory treatment, but it means researchers have identified a plausible chemical component behind at least part of calendula’s traditional association with inflamed skin, which is a considerably more interesting conclusion than the plant simply being associated with healing. For centuries herbalists could observe only the plant and the skin; modern analytical chemistry allows us to begin examining the molecular territory between them.

This has practical implications for how calendula extracts are evaluated. An extract containing substantial concentrations of relevant triterpenoids cannot automatically be assumed equivalent to a weak infusion containing very different proportions of compounds, because extraction method determines what actually reaches the formulation. For cosmetic science this means the words contains calendula reveal remarkably little; the more useful questions are which part of the plant, extracted how, into which solvent, at what concentration, and standardised against which constituents. These are less romantic questions than simply asking whether a product contains calendula, but they are considerably more informative.

Flavonoids, carotenoids and phenolic compounds

Calendula flowers contain numerous flavonoids, including derivatives of quercetin and isorhamnetin, which perform several functions within the plant including pigmentation, protection against ultraviolet radiation and interaction with environmental stress, and many demonstrate antioxidant and anti-inflammatory behaviour in laboratory systems. This has contributed to interest in their possible relevance to calendula’s traditional dermatological uses, but a compound demonstrating biological activity in isolation does not establish that a finished calendula cream produces the same effect on human skin. The molecule must be present in sufficient concentration, survive extraction and manufacture, remain stable during storage, be released from the formulation, and reach the biological environment in which the proposed effect could occur. Phytochemistry tells us what might be biologically plausible; clinical research determines whether that plausibility becomes meaningful in people.

The extraordinary yellow, gold and orange colours of calendula flowers arise principally from carotenoid pigments, including members of both the carotene and xanthophyll families, with lutein and related xanthophylls contributing particularly strongly to flower colour. Pale yellow and intensely orange cultivars do not possess precisely the same pigment profile, and selective breeding, growing conditions and flower maturity can all influence colour and therefore carotenoid composition. Carotenoids are particularly interesting biologically because many possess antioxidant properties and can interact with reactive oxygen species, encouraging investigation of their potential contribution to skin-related botanical extracts, though the presence of antioxidant compounds does not automatically make a product clinically anti-ageing, nor establish that applying calendula to the skin meaningfully prevents oxidative damage in humans. Calendula also contains additional phenolic compounds beyond its flavonoid fraction, widespread throughout plants and contributing to defence against environmental stress, pathogens and ultraviolet radiation, many of which demonstrate antioxidant behaviour in laboratory assays. Such assays are particularly vulnerable to overinterpretation, however, since a high result in a DPPH or similar chemical assay does not tell us how effectively an ingredient protects living human skin, whose antioxidant systems involve enzymes, lipids, proteins, vitamins and continual interaction with the external environment.

Polysaccharides and volatile constituents

Among calendula’s less visually dramatic constituents are polysaccharides, large carbohydrate molecules occurring throughout plant tissues that may contribute to structural and physiological functions, and certain fractions have demonstrated biological activity relevant to immune and inflammatory processes in experimental research, though their significance following topical cosmetic application remains considerably less established than their presence in the plant. Calendula is aromatic but is not an essential-oil plant in the same sense as lavender, rosemary or peppermint; its flowers contain volatile mono- and sesquiterpenes, but these represent a relatively small component compared with the abundant volatile oils produced by specialised aromatic species. This explains why calendula’s role in skincare developed primarily around extracts and macerates rather than essential oil, and why calendula-infused oil should never be confused with calendula essential oil, since the first is produced by extracting flower constituents into a fixed carrier oil while the second would refer to a concentrated volatile fraction obtained through distillation. They are chemically and functionally different materials.

Perhaps the most important lesson from calendula chemistry is that extraction determines composition. A hydroalcoholic extract may recover a broad range of flavonoids and other polar-to-intermediate compounds, an aqueous preparation preferentially extracts water-soluble constituents, an oil macerate favours lipophilic compounds, and a supercritical carbon-dioxide extract can concentrate yet another chemical fraction. None should automatically be regarded as superior; they simply represent different interpretations of the same plant. If a laboratory study demonstrates activity using a concentrated ethanol extract, it does not follow that a cosmetic containing a small quantity of calendula-infused sunflower oil will produce an equivalent biological response. Botanical evidence belongs not merely to the species, but to the species, plant part, extraction method, chemical composition, concentration and formulation used in the study, and ignoring those distinctions is one of the easiest ways to exaggerate botanical science.

Calendula’s chemistry provides several biologically plausible explanations for its traditional association with irritated and recovering skin. Triterpenoids may influence inflammatory processes, flavonoids and phenolic compounds demonstrate antioxidant activity, carotenoids contribute additional antioxidant chemistry, and experimental extracts have demonstrated effects involving fibroblasts, keratinocytes and inflammatory signalling. But plausibility is not proof. The chemistry tells us that the historical reputation of calendula is worthy of serious investigation. It does not tell us that every historical claim is correct, and to understand that distinction properly we first need to understand something even more remarkable than calendula: how skin repairs itself.

How skin heals

The word healing appears so frequently in skincare that it can begin to sound almost meaningless, as creams, oils, botanicals and serums promise to heal or accelerate healing. Yet biological healing is not a single event. It is an extraordinarily coordinated sequence involving blood vessels, immune cells, structural proteins, signalling molecules and several different populations of skin cells. A wound does not simply close; the body must first prevent blood loss, control contamination, remove damaged tissue, construct temporary replacement tissue, rebuild the epidermal barrier and then remodel that new tissue over weeks or months. These processes overlap rather than occurring as perfectly separated stages, but they are conventionally described as four broad phases: haemostasis, inflammation, proliferation and remodelling. Understanding these stages changes the question we ask about calendula. Instead of asking does calendula heal wounds, we can ask something much more scientifically useful: is there evidence that calendula influences any of the biological processes involved in normal tissue repair?

Haemostasis and inflammation

The body’s first priority following significant disruption of the skin is to stop the bleeding. Damage to blood vessels triggers immediate vascular responses, platelets adhere to exposed structures within the damaged vessel wall and aggregate, and the coagulation cascade produces fibrin, creating a stabilising mesh around the developing platelet plug. The resulting clot limits blood loss, provides a temporary physical barrier, and creates an extracellular matrix through which cells involved in subsequent repair can migrate. Calendula’s traditional reputation is not principally associated with haemostasis, and there is currently insufficient evidence to suggest it should be regarded as a clinically meaningful haemostatic agent, an important limitation given that a botanical associated generally with wound healing should not automatically be assumed to influence every stage of the process.

Once immediate bleeding is controlled, the wound enters a highly coordinated inflammatory phase. Inflammation is frequently portrayed negatively in skincare, which is misleading, since without inflammation normal wound repair cannot occur. Neutrophils arrive rapidly to help control microorganisms and clear damaged material, macrophages remove cellular debris while releasing signalling molecules that help coordinate later stages of repair, and cytokines and chemokines act as molecular messages, recruiting cells and regulating their behaviour. The objective is not simply to create inflammation but to produce a response appropriate to the injury and then resolve it at the appropriate time, since too little inflammation can impair defence while too much or prolonged inflammation can delay repair and contribute to chronic wounds. This is one reason calendula’s experimental anti-inflammatory activity is scientifically interesting, though the relevant question is not whether calendula switches inflammation off, which would not necessarily be desirable, but whether its constituents can modulate inflammatory signalling in ways that might support an orderly transition into subsequent phases of repair. Experimental studies suggest calendula extracts and particular triterpenoid fractions can influence inflammatory pathways; whether these effects translate consistently into clinically meaningful improvements in human wound healing remains much less certain.

Proliferation and remodelling

The proliferative phase is where reconstruction becomes visibly apparent. Fibroblasts migrate into the developing wound and begin producing components of the extracellular matrix, including collagen and other structural molecules that provide the framework for new tissue, participating in an elaborate signalling network governing tissue structure, contraction and repair; some differentiate into myofibroblasts, cells possessing contractile properties that help draw wound edges together. Experimental studies have reported effects of calendula flower extracts upon fibroblast proliferation and markers associated with fibroblast activity, providing biological plausibility for a role in tissue repair, though cellular experiments remain several steps removed from demonstrating improved healing in human patients.

New tissue requires oxygen and nutrients, so new blood vessels begin growing into the wound through angiogenesis, creating the vascular network required to support metabolically active repair tissue, and calendula extracts have demonstrated pro-angiogenic effects in some experimental systems, again intriguing rather than conclusive. The combination of new capillaries, fibroblasts, extracellular matrix and immune cells creates granulation tissue, newly forming connective tissue occupying the wound bed whose development represents an essential stage in normal repair, and several animal studies and some clinical observations involving calendula have reported increased granulation or changes consistent with progression through this stage, one reason wound healing has remained the principal focus of modern calendula research. While deeper tissue is being reconstructed, keratinocytes at the wound margins begin migrating across the surface in re-epithelialisation, ultimately rebuilding the epidermal covering and its barrier structures; research investigating calendula’s effects on keratinocytes has produced complex results, with some experimental extracts influencing inflammatory signalling and cellular activity while evidence for a direct and consistent acceleration of keratinocyte migration is less straightforward. This illustrates why the word healing can conceal more than it explains, since an extract may influence one component of repair without meaningfully changing another.

A wound that appears closed is not necessarily finished healing. The newly formed tissue initially possesses a relatively disorganised extracellular matrix, and over subsequent weeks and months collagen is continually broken down, replaced and reorganised, with the balance between matrix metalloproteinases and their inhibitors helping regulate the process as collagen fibres become more organised, tensile strength increases and vascularity decreases. Even after successful healing, scar tissue generally does not reproduce all the structural characteristics of uninjured skin, and at present there is insufficient clinical evidence to conclude that calendula reliably prevents scarring or restores injured skin to its original structure. Those claims go considerably beyond the available science. Perhaps the most important lesson from wound biology is that healing is not simply a matter of making biological processes happen faster; successful repair depends upon timing, with inflammation beginning and then resolving, fibroblasts and keratinocytes acting in coordinated sequence, and new tissue gradually maturing into something closer to the skin that existed before injury. A botanical extract that influences one part of this sequence has not thereby been shown to improve the whole.

Evidence for skin

Having established what healing actually involves, we can now examine what has been observed when calendula preparations are tested against it, moving from the most robust traditional recognition through to the more specific clinical literature.

Minor skin inflammation and minor wounds

Current evidence: ★★★☆☆ Traditional use, plausible mechanism

This is calendula’s best-established position. The European Medicines Agency’s Committee on Herbal Medicinal Products recognises calendula flower preparations, under its European Union herbal monograph, as traditional herbal medicinal products for the symptomatic treatment of minor skin inflammation, such as sunburn, and as an aid in the healing of minor wounds. That recognition rests on long-standing use, a plausible mechanism and an acceptable safety record, rather than on confirmatory randomised controlled trials, and the HMPC explicitly states that there is insufficient evidence from clinical trials to establish a well-established medicinal use. Traditional use is a genuine and useful regulatory category. It is not equivalent to proven clinical efficacy, and the distinction is worth holding in mind through everything that follows.

Wound healing, more broadly

Current evidence: ★★☆☆☆ Mixed, encouraging in places

A 2019 systematic review examined 14 studies investigating calendula extract and wound healing, comprising seven animal experiments and seven clinical trials, and found reasonably consistent evidence from animal studies of faster resolution of the inflammatory phase and increased granulation tissue formation, while clinical results varied considerably by wound type; the authors concluded that larger, better-designed randomised trials were needed. An earlier systematic review reached an even more cautious position, identifying six randomised controlled trials of topical calendula monopreparations but considering only one of good methodological quality, and concluding that the evidence for topical calendula in acute and chronic wounds was weak. Neither review concludes that calendula does not work. Both conclude that the evidence available is not yet strong enough to say confidently that it does.

Venous leg ulcers

Current evidence: ★★☆☆☆ Small studies, encouraging

Some of the more encouraging clinical findings involve venous leg ulcers, chronic wounds associated with impaired venous circulation that can be extraordinarily difficult to heal. An early clinical study found that patients treated with a calendula extract ointment experienced a greater reduction in total ulcer surface area over three weeks than those receiving saline dressings, and a later investigation using a defined calendula extract reported a significant increase in healing velocity compared with controls. These are genuinely useful signals, but the studies involved small numbers of patients, and venous ulcers require medical assessment of the underlying vascular disease, compression therapy where appropriate and specialist wound care; a calendula preparation should be understood as a subject for further investigation within that context, not a substitute for it.

Surgical and obstetric wounds

Current evidence: ★★☆☆☆ Small randomised trials, encouraging

Calendula has also been investigated following episiotomy and caesarean section. A randomised trial of 100 women found significantly lower pain from the second day onwards among those using calendula ointment after episiotomy compared with standard care, alongside improvements in wound redness and oedema, and a separate randomised controlled trial of 72 women found that calendula ointment considerably increased the speed of wound healing after caesarean section, assessed using the REEDA scale on days three, six and nine. These are encouraging, well-designed small trials, though replication in larger and more diverse populations would considerably strengthen confidence, and postoperative wounds continue to require appropriate medical care regardless of any complementary topical preparation used alongside it.

Radiation dermatitis

Current evidence: ★☆☆☆☆ Inconsistent across trials

Radiation dermatitis is perhaps the clearest illustration of how calendula’s evidence base has actually developed. A 2004 phase III randomised trial of 254 people receiving radiotherapy for breast cancer found significantly less grade 2 or greater acute dermatitis with calendula ointment than with a trolamine comparator, alongside fewer treatment interruptions and less radiation-associated pain, a result that attracted considerable attention. A later, smaller randomised controlled trial comparing calendula with a standard moisturising cream in women undergoing breast radiotherapy did not detect a significant difference in dermatitis, though the trial was underpowered. A 2023 systematic review and meta-analysis of natural and miscellaneous agents for the prevention of acute radiation dermatitis examined five products, aloe vera, oral enzymes, olive oil, calendula and curcumin, and found that only oral enzymes and olive oil produced a statistically significant reduction in grade 2 or greater dermatitis. Calendula was not among them. Taken together, this body of evidence has moved from an exciting single result towards a more cautious pooled conclusion, which is a demonstration of the scientific process working correctly rather than calendula having failed.

General skin comfort and conditioning

Current evidence: ★★☆☆☆ Plausible, cosmetic role

Away from clinical wound and dermatitis research, calendula’s most defensible modern role may simply be cosmetic. A well-formulated calendula product can provide emollience through its carrier oils, contribute botanical constituents with plausible anti-inflammatory and antioxidant activity, and support the sensory character of a formulation intended for comfort or conditioning, none of which requires a claim that the finished product treats disease. This does not amount to strong clinical evidence in the way a randomised trial does, but it accurately reflects what a responsibly formulated calendula cosmetic can be expected to contribute, and it may ultimately be where the ingredient fits most comfortably within modern skincare.

Antimicrobial activity and infection

Current evidence: ★☆☆☆☆ Laboratory only

Calendula extracts have demonstrated antimicrobial activity against various microorganisms under experimental conditions, which has contributed to claims that calendula can protect wounds against infection. Laboratory contact between an isolated microorganism and a concentrated extract at a controlled concentration is fundamentally different from a living wound, which contains tissue, proteins, immune cells and complex microbial communities, and a cosmetic formulation typically delivers considerably lower concentrations of active compounds than a laboratory assay. Calendula should not be considered a replacement for validated antiseptic products where antisepsis is required, nor should a calendula-containing cosmetic be assumed to preserve itself; botanical antimicrobial activity does not eliminate the requirement for an effective cosmetic preservation system.

Evidence for hair and scalp

Calendula is overwhelmingly associated with skincare. Unlike rosemary, peppermint or certain other botanicals frequently promoted within contemporary haircare, Calendula officinalis has not developed a substantial scientific literature concerning hair growth, though calendula extracts do appear in shampoos, scalp treatments, conditioners and products intended for dry or sensitive scalps. The rationale for their inclusion is generally not a direct effect upon the hair follicle but the fact that the scalp is skin, possessing a complex epidermal barrier, sebaceous glands, immune cells and microbial communities, and that irritation, excessive dryness and disruption of this environment may contribute to discomfort even when the follicle itself remains healthy. Calendula’s investigated anti-inflammatory, antioxidant and skin-conditioning properties provide a plausible reason for inclusion in scalp-care formulations, but the important question is how much of that plausibility has been demonstrated clinically, and at present the answer is relatively little.

Scalp comfort and scalp barrier

Current evidence: ★☆☆☆☆ Limited

Dryness, itching and irritation are common scalp complaints arising from causes including harsh cleansing, environmental exposure, cosmetic treatments, allergic contact dermatitis, seborrhoeic dermatitis and underlying dermatological disease. Calendula is frequently incorporated into products marketed for sensitive or uncomfortable scalps because experimental evidence suggests its extracts can influence inflammatory processes, which provides biological plausibility, but clinical research specifically evaluating calendula for scalp irritation remains sparse, and much of the available evidence concerning its soothing properties derives from studies involving skin elsewhere on the body. A carefully formulated calendula product may therefore contribute to scalp comfort, particularly where dryness or mild irritation is present, but this should be understood as a supportive cosmetic role rather than a treatment for scalp disease. The scalp’s epidermal barrier performs many of the same functions as skin elsewhere, limiting water loss and restricting penetration of environmental substances, and while calendula’s chemistry makes its inclusion in barrier-conscious formulations plausible, there is currently insufficient clinical evidence that it independently restores or substantially improves scalp barrier function; its role is more reasonably understood as one component within a wider formulation alongside humectants, emollients, occlusives and appropriate surfactants.

Dandruff and hair growth

Current evidence: ★☆☆☆☆ Very limited

Calendula is sometimes described online as a natural treatment for dandruff, but the evidence supporting this is weak. Dandruff and seborrhoeic dermatitis are complex conditions involving interactions between sebaceous activity, individual susceptibility, epidermal function and yeasts of the genus Malassezia, and although calendula extracts have demonstrated general antimicrobial activity experimentally, this does not demonstrate clinically meaningful anti-dandruff activity or that calendula can control Malassezia sufficiently when incorporated into a normal cosmetic formulation. Ingredients specifically developed and evaluated for dandruff possess considerably stronger evidence. Claims that calendula stimulates hair growth appear increasingly within botanical haircare marketing, and there is little convincing evidence to support them; hair growth is controlled by a sophisticated biological cycle involving the follicle, dermal papilla, hormones, signalling pathways, nutrition, genetics and immune function, and demonstrating that a plant possesses antioxidant or anti-inflammatory activity is not sufficient to establish that it stimulates human hair follicles. At present there is no substantial body of high-quality human clinical evidence that topical calendula significantly increases hair density, reverses androgenetic alopecia or treats other common forms of hair loss. An ingredient can contribute to a comfortable scalp without altering the biology of hair growth, and calendula currently fits far more convincingly into the first category. Once a hair shaft emerges from the follicle it consists largely of keratinised cells that are no longer biologically active, so damaged hair cannot heal in the same sense as living skin; cosmetic conditioners can coat damaged areas, reduce friction and temporarily improve feel and shine, but there is little evidence that calendula extracts themselves produce meaningful structural repair, and much of the softness attributed to a calendula-containing conditioner is more likely to arise from the complete formulation than from calendula alone.

Calendula therefore has a plausible but modest place within scalp care, with its greatest potential lying in formulations designed around comfort, mildness and the maintenance of healthy scalp skin, and considerably less evidence for direct effects upon the hair itself. A botanical does not need to perform every conceivable function to be useful. Sometimes a supporting role is enough.

What the evidence does not support

Calendula occupies an unusually favourable position within popular herbal culture, surrounded by words such as gentle, soothing, healing, regenerative and natural. Some of these descriptions have a legitimate scientific foundation. Others have gradually expanded beyond the evidence supporting them, and the distinction matters because calendula is often incorporated into products intended for precisely those consumers whose skin may already be vulnerable, including babies, people with sensitive skin and individuals seeking products for compromised skin. Responsible botanical science therefore requires us to ask not only what calendula might do, but what we should not claim that it does.

Calendula is not a universal wound treatment. Modern experimental research provides legitimate reasons for scientific interest, with calendula preparations demonstrating effects relevant to inflammatory signalling, fibroblast activity, granulation tissue and other processes involved in experimental wound repair, but supporting normal biological processes is not equivalent to treating every wound. A superficial abrasion is fundamentally different from a deep laceration, an infected wound, a diabetic ulcer, a pressure ulcer, a surgical wound, a severe burn, a wound involving significant tissue loss, or a wound associated with impaired circulation, and such injuries may require medical assessment, infection control, specialised dressings, surgical intervention or management of underlying disease. No botanical preparation should delay appropriate healthcare, and calendula’s historical reputation should never be interpreted as permission to treat serious wounds at home.

Healing is not a single biological effect. As set out earlier in this monograph, wound repair involves overlapping phases of haemostasis, inflammation, proliferation and remodelling, with different cells, cytokines, growth factors and structural proteins participating at different stages, so demonstrating that a calendula extract affects one laboratory marker involved in inflammation does not demonstrate that it accelerates the entire healing process in humans. Mechanistic evidence helps explain what might occur; clinical evidence determines whether that possibility becomes meaningful in real people, and confusing these two forms of evidence is one of the most common ways botanical claims become exaggerated.

Calendula does not prevent or erase scarring. Scar formation is influenced by wound depth, anatomical location, infection, mechanical tension, genetics, age, inflammatory response, wound management and individual predisposition to hypertrophic or keloid scarring, and an ingredient capable of influencing aspects of experimental wound repair cannot automatically be assumed to prevent clinically significant scarring or restore mature scar tissue to its original state. Over time many scars naturally become flatter, paler and less noticeable, and when botanical products are used throughout that period, natural improvement can easily be misattributed to the product itself.

Calendula is not a proven treatment for eczema or psoriasis. Atopic dermatitis is a complex inflammatory skin disease involving barrier dysfunction, immune dysregulation, genetic factors and environmental triggers, and psoriasis is an immune-mediated inflammatory disease involving accelerated keratinocyte turnover and complex immune signalling; laboratory evidence of anti-inflammatory activity from calendula extracts does not establish clinical efficacy against either condition. Calendula-containing products may provide emollience or improve subjective skin comfort depending upon the formulation, which is very different from treating the underlying disease, and a botanical ingredient may complement good skin care without replacing appropriate dermatological management.

Antioxidant activity does not mean anti-ageing, and antimicrobial activity does not mean antiseptic. Skin ageing reflects cumulative changes involving collagen organisation, elastin, pigmentation, cellular senescence, oxidative stress and decades of environmental exposure, and there is currently insufficient evidence that topical calendula meaningfully reverses established wrinkles or restores aged skin structure; broad-spectrum sunscreen and certain well-established topical actives possess substantially stronger evidence. Natural does not mean hypoallergenic either. Plants manufacture biologically active chemicals for their own ecological purposes, and calendula belongs to the Asteraceae, a family that includes plants capable of causing contact allergy; for most people this presents little difficulty, but for a susceptible minority botanical origin offers no guarantee of tolerance.

More calendula is not necessarily better. Increasing the concentration of an extract may alter colour, odour, viscosity, stability, preservation, compatibility with other ingredients and irritation potential, and an effective formulation uses enough of an ingredient to achieve its intended function while maintaining safety, stability and sensory quality. Botanical abundance is not a substitute for formulation science. And tradition is valuable but it is not proof: centuries of use tell us that generations of people considered calendula useful enough to cultivate, preserve and repeatedly incorporate into household preparations, which deserves respect, but historical observations were made without randomisation, control groups, blinded assessment or modern diagnostic criteria. Traditional knowledge can identify valuable research questions. It cannot answer them by itself. The most respectful approach to traditional botanical knowledge is therefore neither unquestioning acceptance nor casual dismissal, but investigation.

Removing exaggerated claims does not make calendula less interesting. It makes it more interesting. What remains is a plant with an unusually persistent historical association with damaged and irritated skin, chemically diverse flowers, biologically plausible mechanisms and an emerging, still imperfect, scientific evidence base, which is a far more credible story than calling calendula a miracle healer. The scientific question is no longer does calendula heal everything. It becomes which preparations of calendula influence which biological processes, at what concentrations, under what conditions, and do those effects produce meaningful benefits in human skin. That is a question worthy of serious investigation.

Safety, contraindications and regulatory considerations

Calendula is widely perceived as one of the gentlest botanical ingredients used in skincare, and for most people appropriately manufactured calendula-containing cosmetics appear to be well tolerated. A responsible safety assessment must nonetheless distinguish between broad tolerability and universal safety, since no biologically active botanical is incapable of causing an adverse reaction, and calendula is no exception.

Calendula officinalis belongs to the botanical family Asteraceae, historically also called Compositae, one of the largest families of flowering plants and one that includes chamomile, arnica, echinacea, chrysanthemums, daisies, sunflowers, yarrow, feverfew and ragweed. Several members of this family are recognised causes of allergic contact dermatitis, with sesquiterpene lactones particularly important among the responsible allergens, and while calendula’s sensitising potential appears relatively low compared with some members of the family, documented reactions exist. Describing calendula as inherently hypoallergenic would therefore be inappropriate.

Allergic contact dermatitis is a delayed immune reaction occurring after an individual becomes sensitised to a particular substance, with subsequent exposure potentially causing redness, itching, swelling, scaling, vesicles or dermatitis. Calendula-related allergic contact dermatitis appears uncommon, but cases have been reported, and individuals already sensitised to plants within the Asteraceae family may warrant particular caution because cross-reactivity can occur between related botanical allergens. This does not mean everyone with hay fever or a general pollen allergy will react to calendula on the skin, since respiratory pollen allergy and allergic contact dermatitis involve different patterns of exposure and immune response, but consumers with an established contact allergy to Asteraceae botanicals should examine calendula-containing products carefully. Irritation and allergy are frequently confused: irritant contact dermatitis occurs when a substance directly damages or disrupts the skin and does not require prior sensitisation, while allergic contact dermatitis is an immune-mediated response that develops only in sensitised individuals, and a person may react to a calendula-containing product without necessarily being allergic to calendula itself, since fragrance, preservatives, surfactants, emulsifiers or other botanical extracts within the same formulation may be responsible. Determining the cause of recurrent dermatitis may therefore require formal patch testing performed by an appropriately qualified dermatologist.

Calendula is frequently marketed specifically towards sensitive skin, which is understandable given its traditional use and experimental anti-inflammatory activity, but sensitive skin is not a single medical diagnosis. People describing their skin as sensitive may be experiencing impaired barrier function, irritant reactions, rosacea, atopic dermatitis, allergic contact dermatitis, environmental sensitivity or reactions to specific cosmetic ingredients, and a product suitable for one of these individuals may be unsuitable for another. The quality of the finished formulation therefore matters considerably more than the presence of the word calendula on the label.

The long historical association between calendula and wounds requires a particularly important safety distinction: a cosmetic product is not automatically suitable for use on an open wound. Products designed for intact skin are manufactured and assessed according to that intended use, and applying them to significantly damaged tissue changes the route and degree of exposure and may increase the risk of contamination or irritation. Minor superficial skin damage and serious wounds should never be treated as equivalent, and deep, infected, heavily bleeding, non-healing or otherwise concerning wounds require appropriate medical assessment.

Calendula-containing cosmetic products generally involve relatively low topical exposure, but evidence concerning concentrated calendula preparations during pregnancy and breastfeeding is limited, common across botanical medicine because pregnant populations are understandably underrepresented in clinical research. Routine use of a properly formulated cosmetic is fundamentally different from consuming concentrated herbal preparations or using medicinal extracts, and these routes of exposure should not be conflated; anyone considering concentrated calendula preparations for therapeutic purposes during pregnancy or breastfeeding should seek appropriate professional advice.

Calendula appears frequently in baby creams, nappy-area products and children’s skincare, partly reflecting its reputation for gentleness, but infant skin requires particularly thoughtful formulation. The skin barrier continues to develop after birth, and infants possess a much greater skin-surface-area-to-body-weight ratio than adults, so products intended for babies should be formulated specifically for that population rather than created by simply adding calendula to an adult cosmetic formulation. Fragrance, preservation, pH, potential allergens and the entire ingredient system require consideration, and the presence of calendula does not, on its own, determine the suitability or safety of a product for infant use.

Sustainability, cultivation and supply chain

Calendula sits in a very different sustainability position from many of the botanicals examined elsewhere in this Library. Rose requires an enormous mass of hand-harvested flowers for a small yield of aromatic material, and sea buckthorn’s harvest is complicated by thorny branches and fruit that ruptures easily; calendula is, by comparison, an unusually undemanding crop. It is a fast-growing annual that germinates readily, tolerates a range of soils and climates, flowers repeatedly across a long season, and is already cultivated widely across Europe and beyond for ornamental, culinary and cosmetic markets. It does not appear on conservation watch lists, and there is no equivalent to the wild-harvesting pressure that affects some slower-growing or more geographically restricted botanicals.

That relative ease of cultivation does not remove the need for responsible sourcing. Calendula grown as a conventional agricultural crop is still subject to the usual questions surrounding pesticide use, soil health, water management and labour conditions, and organic and other third-party certifications remain the most reliable way for a formulator to verify claims made about cultivation practice rather than relying on the reassuring word natural. Because the flower heads are harvested by hand or with relatively simple mechanical aids across an extended flowering season, calendula cultivation has also found a place within smallholder and cooperative farming models in parts of Europe and further afield, where a repeatedly harvestable flower crop can provide a more distributed and resilient source of income across a growing season than a single annual harvest. For a brand assessing supply chains, this makes calendula a useful test case for asking not only whether a raw material is available at scale, but who actually grows it and on what terms.

Post-harvest handling meaningfully affects the finished ingredient. Because much of calendula’s interest resides in constituents such as carotenoids and triterpenoids that can degrade with excessive heat, prolonged light exposure or poor storage, drying and storage conditions influence both the colour and the chemical profile of the dried flower and any extract subsequently prepared from it. A supplier able to describe drying method, storage conditions and time between harvest and processing is providing meaningfully more useful information than one offering only the species name, and this is one further instance of a theme that recurs throughout this monograph: with a botanical as widely available as calendula, the interesting sourcing questions are rarely about scarcity, and almost always about traceability and care.

Cosmetic formulation

A botanical ingredient does not enter a cosmetic formulation simply because its history is compelling or its laboratory evidence is interesting. It must also work: remain sufficiently stable throughout the intended shelf life, interact appropriately with other ingredients, tolerate manufacturing conditions, and be present in a form capable of contributing whatever properties the formulator expects from it. Calendula illustrates this particularly well, because there is no single cosmetic ingredient called simply calendula, and asking how much calendula should be included in a formulation is rather like asking how much rose should be used without specifying whether one means rose essential oil, rose water or rosehip seed oil. The preparation matters.

Scientific literature generally refers to the plant as Calendula officinalis L., while cosmetic formulations use names established through the International Nomenclature of Cosmetic Ingredients system, and depending upon the raw material, ingredient declarations may include names associated with calendula flower, flower extract or flower-derived preparations. The precise INCI designation should always be confirmed against the supplier’s technical documentation for the specific material being purchased, since apparently similar commercial extracts may differ substantially in solvent system, concentration and composition, and a formulator should never assume that two supplier ingredients carrying the word calendula are interchangeable.

As discussed under Ingredient Forms, calendula oil macerates inherit much of their oxidative behaviour from the carrier oil, since unsaturated vegetable oils gradually oxidise when exposed to oxygen, heat and light, producing undesirable odours, colour changes and degradation products that shorten shelf life. Responsible formulation may involve selecting appropriately stable carrier oils, protecting raw materials from heat and light, minimising unnecessary exposure to air, incorporating antioxidants where appropriate, selecting suitable packaging and performing accelerated and real-time stability testing. Vitamin E, particularly tocopherol, is frequently incorporated into anhydrous botanical formulations as an antioxidant, though an antioxidant is not a preservative; vitamin E may help slow oxidation of oils but does not provide adequate protection against microbial contamination in water-containing formulations, a distinction that becomes essential once water enters the picture. Any cosmetic containing sufficient available water to support microbial growth requires an appropriately designed preservation strategy, and calendula itself should never be relied upon to preserve a cosmetic product; laboratory reports of antimicrobial activity do not establish that a botanical extract can function as a validated broad-spectrum cosmetic preservative, and a preservation system must be selected for the complete formulation and validated appropriately, including through microbiological challenge testing where required. Natural does not exempt a product from microbiology.

Botanical extracts can contain compounds susceptible to prolonged heat exposure, so where supplier specifications permit, formulators may incorporate certain calendula extracts during the cooling phase of an emulsion rather than subjecting them unnecessarily to high manufacturing temperatures, although oil macerates used as part of an oil phase may tolerate normal processing conditions; individual supplier guidance should always take precedence over general assumptions. Calendula itself does not impose a single universal formulation pH, and the appropriate pH depends upon the complete formulation, including preservative system, emulsifier, other active ingredients and intended site of application; products intended for facial skin will commonly be formulated within a mildly acidic range compatible with normal skin physiology, but calendula does not remove the need for routine pH optimisation and stability assessment.

Calendula is unusually versatile in formulation because its botanical character is gentle rather than aromatically dominant, and it sits comfortably beside both traditional botanicals and modern cosmetic ingredients. Oats bring a substantial modern dermatological literature concerning dry, itchy and compromised skin, creating an interesting bridge between traditional botanical practice and contemporary barrier-focused skincare. Chamomile shares calendula’s historical association with soothing preparations, though both belong to Asteraceae, worth remembering for individuals with relevant plant allergies. Jojoba provides an elegant carrier for oil-based calendula formulations, offering excellent oxidative stability and a relatively light skin feel, while squalane offers similar stability while contributing little colour or fragrance of its own, allowing calendula’s botanical character to remain visually prominent. Ceramides and calendula represent two very different formulation philosophies that can work surprisingly well together, calendula providing botanical character and potentially useful supportive biological activity, ceramides providing a much more directly established approach to supporting epidermal barrier lipids; there is no reason botanical and modern cosmetic science need to compete, and often the more interesting formulations allow them to coexist. Panthenol, with its humectant and conditioning properties, is another logical companion in formulations designed around skin comfort and barrier support.

Balms are perhaps the most historically intuitive calendula product, combining a calendula macerate with carefully selected emollients, waxes and antioxidants; the absence of water simplifies microbial control, the lipid-rich base can reduce transepidermal water loss through occlusion, and the golden colour of calendula may become part of the product’s sensory identity. Even here, it is important to distinguish the effect of the entire formulation from the effect of calendula alone, since a well-formulated balm may improve dry skin substantially because of its oils, waxes and occlusive properties even if calendula’s own biological contribution is modest. Creams and lotions instead allow calendula to be combined with humectants, emollients, barrier lipids and other functional ingredients, which may ultimately be where calendula is most interesting: rather than asking the botanical to perform every function itself, the formulator can give each ingredient a defined role, with humectants attracting water, emollients improving skin feel, occlusives reducing water loss, ceramides contributing barrier lipids, preservatives protecting the formulation, and calendula contributing its selected botanical constituents and product identity. This is a more sophisticated approach than constructing a formulation around the idea that one botanical must somehow accomplish everything, and it captures the philosophy of Botanicals and Company particularly well. The romance of plants does not disappear when science arrives. It simply becomes measurable.

Regulatory status, standards and quality assurance

Calendula occupies an unusually interesting regulatory position because it exists simultaneously within cosmetics, traditional herbal medicine and general botanical commerce, and the same plant may appear in products governed by very different legal frameworks. The decisive factor is not simply the ingredient; it is what the finished product is presented as doing. A cosmetic containing calendula may be intended to cleanse, condition, protect or maintain the skin in good condition, and within that context calendula functions as a cosmetic ingredient, but claims change the picture. If a manufacturer begins claiming that a calendula cream treats infected wounds, cures eczema or treats another disease, the product may cross from cosmetic claims into medicinal territory, and this matters particularly for calendula because traditional language surrounding the plant frequently uses words such as healing, wound healing, medicinal, therapeutic, anti-inflammatory and antiseptic, some of which may carry regulatory implications depending upon context and jurisdiction. Responsible botanical brands need to understand not only whether an ingredient has interesting biological properties, but what they are legally permitted to say about the finished product.

Calendula provides a particularly useful example of the distinction between tradition and established clinical efficacy. The European Medicines Agency’s Committee on Herbal Medicinal Products has evaluated Calendula officinalis L. flower under its European Union herbal monograph, procedure EMA/HMPC/437450/2017, adopted 27 March 2018, and calendula flower preparations carry a recognised traditional-use basis for minor inflammation of the skin and as an aid in the healing of minor wounds. That wording is significant: traditional use does not mean modern clinical trials have conclusively demonstrated efficacy, but reflects long-standing use, plausible effectiveness and an acceptable safety history under the conditions considered by the monograph. The HMPC has examined clinical research involving conditions including burns, venous ulcers and inflammatory skin reactions, but methodological limitations prevent firm conclusions from being drawn across the evidence base. Calendula therefore provides an almost perfect lesson in evidence terminology. Traditional recognition is evidence of tradition. It is not automatically evidence of proven clinical efficacy.

Cosmetics marketed within the European Union are governed principally by Regulation (EC) No 1223/2009 on cosmetic products, under which manufacturers and responsible persons must ensure finished products are safe for normal or reasonably foreseeable use, involving appropriate safety assessment, preparation and maintenance of a Product Information File, compliance with Good Manufacturing Practice, appropriate ingredient labelling, product notification, substantiation of cosmetic claims, traceability and monitoring of undesirable effects. Botanical ingredients are not exempt from these requirements simply because they have a history of traditional use. Following the United Kingdom’s departure from the European Union, Great Britain operates its own cosmetic regulatory framework, and although much of the underlying safety philosophy remains closely related to the European system, manufacturers selling into both markets must understand the separate administrative requirements applying in each, with Northern Ireland requiring particular attention because of its distinct post-Brexit regulatory arrangements.

Modern cosmetic manufacture relies upon controlled systems rather than artisanal intuition alone, and ISO 22716 provides internationally recognised guidance for cosmetic Good Manufacturing Practice, addressing personnel, premises, equipment, raw materials, production, finished products, quality control, documentation, deviations, complaints, recalls and storage. For botanical ingredients, documentation is especially important because natural raw materials inherently vary, and the first quality question should be extraordinarily simple: is the plant actually what the supplier says it is? For calendula, the intended species is normally Calendula officinalis L., which should not be confused with plants commonly called marigolds belonging to the genus Tagetes, and reliable supply chains begin with botanical identification, ideally establishing scientific name, plant part, geographical origin, cultivation or collection status, extraction method, extraction solvent, carrier material where applicable and batch identity. Botanical nomenclature is not decorative Latin. It is part of quality assurance.

Professional cosmetic formulators should obtain appropriate technical documentation from suppliers, which may include a specification sheet, Certificate of Analysis, Safety Data Sheet, microbiological limits, extraction ratio, solvent information, carrier-oil identity, pesticide information, heavy-metal specifications, allergen information, storage recommendations, shelf life and country of origin, with precise requirements varying according to ingredient and intended application. Calendula does not face quite the same economic incentives for adulteration as extremely expensive materials such as rose oil or saffron, but substitution, contamination and misidentification remain possible within botanical supply chains: dried flower material may vary in the proportion of petals, receptacles and other plant matter, extracts may differ greatly in strength, oil macerates may contain different carrier oils, and colour may be influenced by cultivar, harvest and storage. The phrase contains calendula therefore tells us remarkably little about the quality of the ingredient. Traceability provides the missing information.

Plants grow in soil and interact continuously with their environment, so botanical raw materials may carry contaminants unrelated to the desirable chemistry of the plant, including pesticide residues, heavy metals, environmental contaminants, microorganisms and foreign botanical matter, making appropriate supplier qualification and raw-material testing part of responsible botanical formulation; the more natural the raw material, the more important good quality control becomes, not less. One further challenge in interpreting calendula research is that experimental preparations are not necessarily chemically equivalent, since a hydroalcoholic extract used in one clinical study may differ substantially from an oil macerate used in a cosmetic balm, complicating both research interpretation and commercial formulation. Where extracts are standardised to defined constituents or manufacturing parameters, comparison becomes easier; where they are not, the word calendula may conceal considerable chemical variation, which is one reason evidence from a particular research extract cannot automatically be transferred to every commercial product containing the same botanical species. A high-quality calendula formulation begins long before ingredients enter the mixing vessel, with seed and soil, cultivation, harvest, drying, storage, extraction, transport, raw-material testing, formulation, manufacture, packaging, stability testing, safety assessment and finally communication with the consumer, and a weakness at any stage can undermine the quality of everything that follows. Botanical formulation therefore requires something rather more demanding than an affection for plants. It requires systems.

Where I think calendula fits

After exploring calendula’s botany, history, chemistry, extraction, wound-healing research and cosmetic applications, I return to the question that matters most to me. Would I formulate with it? Yes. In fact, calendula is one of the botanicals I find most compelling, but perhaps not for the reason people expect. Its appeal does not come from believing that calendula possesses some extraordinary ability to heal skin. That word is used far too casually. Human skin heals because it possesses an astonishing biological repair system involving immune cells, keratinocytes, fibroblasts, blood vessels, extracellular matrix, growth factors and signalling pathways operating in tightly coordinated sequence. No flower performs that process for us.

What calendula may do is rather more subtle. The available evidence suggests biologically plausible effects relevant to inflammation and tissue repair, experimental research is interesting, some clinical findings are encouraging, and traditional use is unusually persistent. The European herbal assessment recognises that history while remaining appropriately cautious about the limitations of clinical evidence, and that is precisely the sort of botanical I want in this Library: not a miracle ingredient dressed up in scientific language, but a genuinely interesting plant whose reputation deserves careful, honest examination rather than either uncritical repetition or reflexive scepticism.

I am particularly drawn to how much calendula rewards asking better questions. Not does it heal, but which preparation, at what concentration, for which purpose, supported by which evidence. That is a harder story to put on a label than healing balm, and I think it is a considerably more honest one. Calendula does not need to be a miracle to be worth including in a formulation. It needs to be understood, sourced with care, extracted appropriately for its intended purpose, and described accurately. Everything else, the colour, the history, the centuries beside cottage doors, is a genuine bonus rather than a substitute for that discipline.

Continue exploring

Disclaimer

The information contained within this monograph is provided solely for educational and informational purposes. Every effort has been made to ensure that the scientific information reflects the published evidence available at the time of writing, but botanical and cosmetic science continue to evolve. Nothing here should be interpreted as medical advice or a recommendation to diagnose, treat, cure or prevent any disease. Descriptions of experimental wound healing, radiation dermatitis, venous ulcers or inflammation are included to review the scientific literature and should not be interpreted as recommendations to use calendula preparations therapeutically in place of medical care. Botanical ingredients may cause irritation or allergic reactions in susceptible individuals, particularly those sensitive to the Asteraceae family, and safety depends upon the specific preparation, concentration, formulation, route of exposure, storage and individual concerned. Concentrated or medicinal calendula preparations differ fundamentally from cosmetic raw materials, and cosmetic-grade ingredients should not be consumed or applied to open wounds unless specifically manufactured and labelled for that use. Individuals who are pregnant, breastfeeding or receiving medical treatment should seek qualified healthcare advice before using concentrated botanical preparations therapeutically, and anyone with a wound that is deep, infected, non-healing or otherwise concerning should seek appropriate medical assessment rather than relying on a cosmetic product.

References

The references below represent principal scientific and authoritative sources consulted during preparation of this monograph. Preference has been given to peer-reviewed research, comprehensive reviews, recognised botanical authorities and official regulatory or standards organisations.

Botanical taxonomy

• Royal Botanic Gardens, Kew. Plants of the World Online: Calendula officinalis L. POWO taxon record

Traditional use and regulatory status

• European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). European Union herbal monograph on Calendula officinalis L., flos, revision 1. EMA/HMPC/437450/2017, adopted 27 March 2018. EMA/HMPC monograph
• European Medicines Agency. Assessment report on Calendula officinalis L., flos, revision 1. EMA assessment report
• Regulation (EC) No 1223/2009 on cosmetic products (consolidated version). EUR-Lex
• ISO 22716. Cosmetics, Good Manufacturing Practices (GMP). ISO catalogue

Chemistry and phytochemistry

• Zitterl-Eglseer, K. et al. (1997). Anti-oedematous activities of the main triterpendiol esters of marigold (Calendula officinalis L.). Journal of Ethnopharmacology, 57(2), 139-144. doi:10.1016/S0378-8741(97)00061-5
• An updated review on the multifaceted therapeutic potential of Calendula officinalis L. (2023). Pharmaceuticals. PMC10142266

Wound-healing and dermatology evidence

• Givol, O. et al. (2019). A systematic review of Calendula officinalis extract for wound healing. Wound Repair and Regeneration, 27(5), 548-561. doi:10.1111/wrr.12737
• Leach, M.J. (2008). Calendula officinalis and wound healing: a systematic review. Wounds: A Compendium of Clinical Research and Practice, 20(8), 236-243. ResearchGate record
• Duran, V. et al. (2005). Results of the clinical examination of an ointment with marigold (Calendula officinalis) extract in the treatment of venous leg ulcers. International Journal of Tissue Reactions, 27(3), 101-106.
• Buzzi, M., de Freitas, F. & Winter, M. (2016). Therapeutic effectiveness of a Calendula officinalis extract in venous leg ulcer healing. Journal of Wound Care, 25(12), 732-739. doi:10.12968/jowc.2016.25.12.732
• De Angelis, C. et al. (2022). Use of calendula ointment after episiotomy: a randomized clinical trial. Journal of Maternal-Fetal & Neonatal Medicine, 35(10), 1860-1864. doi:10.1080/14767058.2020.1770219
• Jahdi, F. et al. (2018). The impact of calendula ointment on cesarean wound healing: a randomized controlled clinical trial. Journal of Family Medicine and Primary Care, 7(5), 893-897. doi:10.4103/jfmpc.jfmpc_121_17
• Pommier, P. et al. (2004). Phase III randomized trial of Calendula officinalis compared with trolamine for the prevention of acute dermatitis during irradiation for breast cancer. Journal of Clinical Oncology, 22(8), 1447-1453. doi:10.1200/JCO.2004.07.063
• Siddiquee, S. et al. (2021). Efficacy of topical Calendula officinalis on prevalence of radiation-induced dermatitis: a randomised controlled trial. Australasian Journal of Dermatology, 62(1), e35-e40. doi:10.1111/ajd.13434
• Robijns, J. et al. (2023). Natural and miscellaneous agents for the prevention of acute radiation dermatitis: a systematic review and meta-analysis. Supportive Care in Cancer, 31(3), 195. doi:10.1007/s00520-023-07656-z

Further reading

• The most balanced single overview. The 2023 Pharmaceuticals review covers calendula’s botany, chemistry and therapeutic potential in one comprehensive sweep. Read the record →
• The regulatory anchor. The EMA/HMPC European Union herbal monograph is the single most authoritative statement of what calendula’s traditional use does and does not establish. Read the record →
• The most rigorous wound-healing synthesis. Givol et al. (2019) is the most recent systematic review combining animal and human wound-healing evidence. Read the record →
• The cautionary tale in radiation dermatitis. Reading Pommier (2004) alongside Robijns (2023) side by side is the clearest demonstration in this monograph of how a single exciting trial can be overturned by a later pooled analysis. Read the record →
• The chemistry behind the tradition. Zitterl-Eglseer et al. (1997) is the classic isolation study behind faradiol’s anti-inflammatory reputation. Read the record →