Calendula, well known as one of the ornamental marigolds, blooms month after month from early spring to first frost. Because "calend" means month in Latin, the plant's lengthy flowering season is believed to have given calendula its name. The herb has been used to heal wounds and treat inflamed skin since ancient times.
An active ingredient that might be responsible for calendula's traditional medicinal properties has not been discovered. One theory suggests that volatile oils in the plant act synergistically with other constituents called xanthophylls.1
Experiments on rats and other animals suggest that calendula cream exerts wound-healing and anti-inflammatory effects,2,3,4 but double-blind, placebo-controlled studies have not yet been reported. The best study on calendula so far was a controlled trial comparing calendula to the standard treatment trolamine for the prevention of skin irriation caused by radiation therapy.6 Interestingly, the researchers used trolamine for comparison not because it has been proven effective but more as a kind of acceptable placebo (trolamine is not thought to do very much, even though it's widely used). The study found calendula more effective than trolamine. However, because this was not a double-blind study, the results mean little; mere expectation of benefit is likely to cause patients and experimenters to perceive benefit.
Creams made with calendula flower are a nearly ubiquitous item in the German medicine chest, used for everything from children's scrapes to eczema, burns, and poorly healing wounds. These same German products are widely available in the United States as well.
Calendula cream is also used to soothe hemorrhoids and varicose veins, and the tea reportedly reduces the discomfort of canker sores. However, as yet there is no scientific evidence for any of these uses.
Calendula cream is generally applied 2 or 3 times daily to the affected area. For oral use as a mouthwash, pour boiling water over 1 to 2 teaspoons of calendula flowers and allow to steep for 10 to 15 minutes.
Calendula is generally regarded as safe. Neither calendula cream nor calendula taken internally has been associated with any adverse effects other than occasional allergic reactions, and animal studies have found no significant toxic effects.5 However, the same studies found that in high doses, calendula acts like a sedative and also reduces blood pressure. For this reason, it might not be safe to combine calendula with sedative or blood pressure medications.
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1. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physicians' Guide to Herbal Medicine. 3rd ed. Berlin, Germany: Springer-Verlag; 1998:259.
2. Review of Natural Products. St. Louis, Mo: Facts and Comparisons; 1995: Calendula monograph.
3. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physicians' Guide to Herbal Medicine. 3rd ed. Berlin, Germany: Springer-Verlag; 1998:259.
4. Patrick KFM, Kumar S, Edwardson PAD, et al. Induction of vascularisation by an aqueous extract of the flowers of Calendula offcinalis L., the European marigold. Phytomedicine. 1996;3:11–18.
5. Bojadjiev C. On the sedative and hypotensive effect of preparations from the plant Calendula officinalis. Nauch Trud Visshi Med Inst Sof. 1964;43:15–20.
6. Pommier P, Gomez F, Sunyach MP, et al. Phase III randomized trial of Calendula officinalis compared with trolamine for the prevention of acute dermatitis during irradiation for breast cancer. J Clin Oncol. 2004;22:1447-53.
Last reviewed December 2015 by EBSCO CAM Review Board
Last Updated: 12/15/2015