Calendula is a genus of flowering annual and perennial plants in the Asteraceae, or daisy, family.
These are the first flowers many of us learn to draw as kids: round center, happy petals, and done. The genus name comes from the Latin word for “little calendar” or “little clock,” which is a rather poetic name for a plant that also happens to show up in creams, oils and teas.
The plant most often discussed for health benefits is Calendula officinalis, also called pot marigold. Important little detail: this is not the same as every ornamental “marigold” you see at the garden center, many of which belong to the Tagetes genus.
The petals of calendula are edible and have traditionally been used fresh in salads or as a natural dye to color certain cheeses. As noted in the Bulletin of the History of Medicine, Calendula has been used medicinally since ancient times.
Virgil (70 BC-19 BC) mentions it under the name “Calta” in his Eclogues. Clearly, this flower has been around the block a few times.
Essential oils and extracts of Calendula officinalis are still studied today for their anti-inflammatory, antioxidant, antimicrobial and wound-healing potential.
What Calendula Is Used For
Unlike many natural remedies that are heavy on folklore and light on research, calendula does have some evidence behind it. That said, the strongest support is not for swallowing large amounts of it or using it as a cure-all, but for topical use, especially for minor skin irritation, mild inflammation and wound care support.
The European Medicines Agency lists calendula flower as a traditional herbal medicinal product used for the symptomatic treatment of minor skin inflammation and minor wounds. It is also used traditionally for minor inflammation in the mouth or throat.
That is a much more reasonable claim than “calendula cures everything,” which thankfully is not where we are going here. Plants can be useful without needing to be magical.
Pharmacological Effects
The use of calendula has been cited in the British and United States Pharmacopeia up until 1905, the U.S. National Formulary as late as 1942, and in the American and National Dispensatories. Today, it is rarely prescribed by clinicians in the way conventional medications are, but calendula still shows up in over-the-counter creams, ointments, oils, teas and herbal preparations.
The active compounds in calendula extracts include:
- Triterpene oligoglycosides
- Saponins
- Flavonol glycosides
- Oleanane-type triterpene oligoglycosides
- Sesquiterpene glycosides
- Carotenoids, including lutein and beta-carotene
- Phenolic compounds
Researchers at the University of Fort Hare in Alice, South Africa, and the University of Lagos, Nigeria, measured the compounds in oils extracted from fresh leaves, dried leaves, and flowers of Calendula officinalis grown in Eastern Cape Province in South Africa in this chemical composition analysis. They found that the percentages of each chemical varied depending on whether the compounds came from flowers or leaves, and whether the leaves were fresh or dried.
In other words, a calendula cream, oil, tea or extract may not all deliver the same mix of compounds. This is where natural products get a little tricky, because “contains calendula” does not always tell you how much, what part of the plant was used, or how it was processed.
Results of experiments on leaves are summarized in Table 1.
Calendula is also rich in antioxidant compounds, including quercetin, lutein, rutin, xanthophylls, ubiquinone and lycopene.
Quercetin has been shown to have antioxidant activity in cell studies, including in vitro research on cultured liver cells from scientists at the Korea Institute of Science and Technology. Of course, cell studies are not the same as human clinical trials, but they can help explain why researchers continue to study calendula’s antioxidant and anti-inflammatory effects.
What Is Oxidative Stress?
Here is the strange thing about oxygen: we need it to live, yet normal oxygen metabolism also produces reactive byproducts called free radicals. These unstable molecules contain an unpaired electron and can damage cells as they try to stabilize themselves.
Free radicals can damage proteins, fats and even DNA. When DNA damage affects genes involved in cell growth and repair, it may contribute to disease development over time.
Free radicals play a key role in cellular inflammation, which is involved in conditions such as obesity, autoimmune disorders, cancer, arthritis, cardiovascular disease and inflammatory bowel disease.
Chronic inflammation is involved in a long list of health conditions, including complications of diabetes, neurological disorders, tumor progression, cardiovascular and pulmonary diseases, bone and joint disorders, autoimmune conditions, and metabolic and endocrine disorders, as reviewed in this inflammation research paper. That does not mean inflammation is always bad, though.
Inflammation is part of normal healing. The problem is when it becomes chronic, excessive or poorly regulated.
Fortunately, the body has its own defense systems to help neutralize free radicals. However, those systems can be overwhelmed by factors such as:
- Illness
- Smoking
- Pollution
- Chronic stress
- Ultraviolet radiation
- Poor diet quality
- Overexertion
- Certain drugs and medical treatments
That is where antioxidant-rich foods and certain plant compounds may help support the body’s normal defenses. Notice the word support, not replace medical care, sunscreen, wound cleaning or a decent diet.
How Calendula May Help Fight Oxidative Stress
In 2015, a team of scientists from Flinders University in Australia demonstrated in vitro that Calendula flower extracts contained bioactive free-radical scavenging compounds that protected cells against oxidative stress in this cell-based study. The effects were both time- and dose-dependent, which researchers often look for when judging whether a compound may be biologically active.
Another study noted that calendula’s effects were influenced by concentration and exposure time, both important details when talking about efficacy. A plant extract may look impressive in a lab dish, but that does not always mean the same result will happen in a person using a store-bought lotion.
A team led by P. Saini in the Department of Periodontics at the Indiana University School of Dentistry looked at calendula’s effects on collagen degradation and matrix metalloprotease activity in human gingival fibroblast cells in vitro. In this gum cell study, a 2% concentration of calendula completely inhibited MMP activity.
Calendula also appeared to inhibit collagen degradation and MMP activity more effectively than a pure solution of quercetin alone. That suggests the benefit may come from a combination of compounds in the plant rather than one single “hero” ingredient.
Calendula for Skin and Wound Healing
Calendula is probably best known for skin use. You will see it in creams, balms, body oils and ointments marketed for dryness, irritation, minor cuts and chapped skin.
The possible skin benefits seem to come from a combination of anti-inflammatory, antioxidant and antimicrobial effects. Some research also suggests calendula may support new tissue formation and collagen activity, which are both important in wound repair.
But this is not a free pass to rub calendula on any wound and call it a day. Deep cuts, burns, infected wounds, animal bites, wounds in people with diabetes, and wounds that are slow to heal should be evaluated by a health professional.
For everyday minor irritation, calendula may be a reasonable ingredient to look for in a topical product. I would still patch test first, especially if you have sensitive skin, because “natural” and “non-irritating” are not always the same thing.
Calendula and Radiation Dermatitis
One area where calendula has been studied in humans is radiation dermatitis, a common side effect of radiation therapy, especially in people receiving treatment for breast cancer. The evidence here is interesting, but also mixed.
Sharp in the Department of Oncology at the Karolinska Institute in Stockholm compared the effects of a commercial calendula cream with Essex cream, a non-perfumed aqueous cream, in 420 patients in this radiation skin reaction trial. Women randomized to the Essex cream arm had a 23% rate of severe acute radiation skin reactions at follow-up, compared with 19% in the calendula group.
Previously, Pommier in the Department of Radiation Oncology at Centre Leon Berard in France conducted a Phase III randomized clinical trial comparing calendula with trolamine for the prevention of radiation dermatitis in women undergoing radiotherapy for breast cancer. In that breast cancer radiotherapy study, grade 2 or higher skin reactions occurred less often in the calendula group than in the trolamine group.
That sounds promising, but it does not mean every calendula cream will work the same way or that patients should start applying it during radiation without asking their oncology team. During cancer treatment, even “gentle” skin products need to be cleared by the care team because timing, ingredients and skin condition matter.
Calendula for Mouth and Throat Irritation
Calendula has also been used traditionally for minor mouth and throat inflammation. The EMA herbal monograph includes this as a traditional use, usually as an infusion, rinse or gargle.
This does not mean calendula tea should replace dental care, antibiotics when needed, or treatment for persistent mouth sores. Mouth ulcers, bleeding gums, white patches, severe sore throat or symptoms lasting more than several days deserve a proper evaluation.
Safety, Side Effects and Who Should Avoid Calendula
Calendula is generally considered well tolerated when used topically by most people. The most likely side effect is an allergic skin reaction, especially in people who are sensitive to plants in the Asteraceae family, such as ragweed, chrysanthemums, daisies and chamomile.
As Memorial Sloan Kettering Cancer Center notes, calendula may cause allergic reactions in sensitive individuals. Pregnant or breastfeeding individuals should be cautious with calendula supplements or concentrated extracts because there is not enough high-quality safety data, and some herbal references advise avoiding medicinal amounts during pregnancy.
Calendula may also interact with sedative medications or other herbs with sedating effects, at least theoretically. This is not usually a concern from a small amount in a skin cream, but it is worth discussing with your doctor or pharmacist if you take medications and are considering oral calendula products.
Another important point: dietary supplements and herbal products are not regulated the same way as prescription drugs in the United States. The FDA explains that supplement companies are responsible for ensuring their products are safe and properly labeled before they are sold.
That means quality can vary quite a bit from one product to another. Look for reputable brands, clear ingredient lists and third-party testing when possible.
Commercially Available Calendula Preparations
Calendula is available commercially as a cream, ointment, salve, body oil, lotion, tincture or tea.
Dried calendula flowers are also sold for use as a hot beverage or as an ingredient in herbal blends. For skin use, calendula is often combined with other ingredients such as beeswax, olive oil, coconut oil, shea butter or aloe.
This is where reading the label matters. Sometimes the calendula is the star of the product, and sometimes it is hanging around at the very end of the ingredient list like it showed up late to the party.
Bottom Line
Calendula has a long history of traditional use and a growing, though still limited, body of research behind it. The best-supported uses are topical, especially for minor skin inflammation, irritation and possibly wound-healing support.
There is also some human research in radiation-related skin reactions, but the evidence is not consistent enough to treat calendula as a standard replacement for medical skin care. Anyone undergoing radiation therapy should ask their oncology team before using calendula or any other topical product.
As for antioxidants, calendula does contain several compounds that may help fight oxidative stress in laboratory studies. But no calendula cream or tea is going to make up for smoking, poor diet, lack of sleep or skipping medical care.
Calendula may be a helpful natural option for minor skin concerns, especially when used in a well-formulated topical product. Just keep the claims realistic, patch test first, and don’t ask a flower to do the job of a doctor.
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