About Herbs

Bottom Line: Calendula is useful as an ointment applied to the skin to reduce painful swelling and irritation associated with radiation therapy. Calendula has not been shown to treat cancer in humans.

Naturally occurring chemicals derived from the marigold plant have been shown to reduce inflammation in laboratory studies. These chemicals called triterpenoids have also been shown to keep the Human Immunodeficiency Virus (HIV) and certain tumor cells from replicating. When applied to the skin, extracts of Calendula reduce inflammation and may help heal cuts, burns and inflammation that occurs as a result of radiation therapy. A liquid that included some calendula extract was shown to reduce ear pain in children with inflammation of the middle ear, but it is unclear to what extent the Calendula extract played a part in that result.

Radiation Therapy Side Effects: 254 breast cancer patients who were undergoing radiation therapy participated in a trial of Calendula to see if it would reduce inflammation of the skin due to radiation therapy. The patients were randomly assigned to receive a topical ointment containing either calendula or trolamine. Trolamine is an accepted treatment for skin inflammation. Subjects who used Calendula had fewer cases of severe skin inflammation. Because the texture, color and smell of the two ointments were quite different, patients knew which treatment they were receiving. Researchers did not know which treatment they had received. This study suggests of Calendula ointment may be used as a preventative treatment for skin inflammation due to radiation therapy.

Calendula officinalis. Family: Asteraceae/Compositae

Gold-bloom, Marigold, Marybud, Pot Marigold

Extracted from the flower of the marigold plant. Calendula is used topically for wound healing and as an anti-inflammatory agent ⁽¹⁾. Major constituents of the leaves and stems of the plant include lutein and beta-carotene ⁽²⁾. Extracts from Calendula have also been shown to have anti-inflammatory properties ⁽³⁾ and anti-HIV activity in vitro ⁽⁴⁾. In addition, some studies suggest that Calendula has cytotoxic and antitumoral activity in vivo ⁽⁵⁾. One clinical trial has shown that topical application can prevent acute dermatitis during postoperative radiation therapy in breast cancer patients ⁽⁶⁾. A formulation that includes Calendula as well as a variety of other herbs was shown to be effective in reducing otalgia in children with acute otitis media ^{(7) (8)}. Calendula has been known to cause allergic reactions ⁽¹⁾.

Flavonoids: Polysaccharides, Terpenoids, Volatile Oils, Other ⁽¹⁾

Triterpenoids from Calendula have been shown to promote anti-inflammatory activity ^{(3) (4)}. The most active triterpenoids is a monoester of faradiol ⁽¹⁾. The organic extract of Calendula has been shown to suppress cell fusion which may inhibit early events in the HIV replication cycle. It is thought that the component that demonstrates activity against HIV is related to these triterpenoids ⁽²⁾. Extracts from Calendula were shown to be cytotoxic and exhibit antitumoral activity in mouse Ehrlich carcinoma, although the effects were not always found to be in parallel ⁽⁵⁾.

Calendula should be avoided during pregnancy and lactation ⁽¹⁾.

Calendula may cause allergic reactions ⁽¹⁾.

Pommier P, Gomez F, Sunyach MP, D'Hombres A, Carrie C, Montbarbon X. 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. 254 patients who had been operated on for breast cancer participated in this study of Calendula and radiation induced dermatitis. Patients were randomized to receive either calendula or trolamine, a routine treatment for topical application during postoperative radiation therapy. Occurrence of grade 2 or higher acute dermatitis was significantly lower in patients who used calendula than those who used trolamine. Because of the differences in texture, color and smell the trial was only single blinded.