Calendula (Calendula officinalis) is a flowering plant in the daisy family that has been traditionally used since the 13th century to treat wounds, digestive problems, and menstrual pain.^[6] The flower petals can be compounded to prepare oral and topical products for medicinal purposes. Calendula can also be consumed as tea. Calendula petals contain flavonoids, compounds which possess antioxidant and anti-inflammatory properties that protect cells from being damaged by radicals, or unstable molecules.^[7] Therefore, it is thought that calendula can fight inflammation. Additionally, calendula is often used to help wounds heal by promoting blood flow to the area.^[8] Calendula should not be confused with the marigold plant, a different orange flower often grown in gardens, which is part of the genus Tagetes.

Calendula has been commonly used for its anti-inflammatory and wound healing effects. Additionally, calendula has been used for conditions like diaper dermatitis in children, vaginal candidiasis, and radiation-induced dermatitis. However, there is limited clinical data to support the use of calendula for medicinal purposes. A case report showed that the use of calendula tincture in a 52-year-old woman with chronic anal fissures achieved improvement and no rectal bleeding after applying the tincture three times a day for 4.5 months.^[9]

One study showed that women who had an episiotomy had more improvement in redness and edema when applying calendula ointment three times a day, compared to control.^[10] Although calendula has demonstrated efficacy for acute wound healing with calendula, studies of chronic wound healing have more varied results. For instance, two studies found venous ulcers improved with the application of calendula, while another clinical trial saw no improvement in diabetic leg ulcers.^[3]

Calendula has been used and studied for the treatment of vaginal candidiasis, and it was found that 5 grams of calendula vaginal cream was just as effective as clotrimazole 1% cream when applied each night for 7 nights with the applicator.^[1] Similarly, one clinical trial found that calendula vaginal cream was effective in the treatment of bacterial vaginosis.^[2]

There is conflicting evidence concerning calendula’s efficacy for radiation-induced dermatitis, and its effectiveness for skin reactions to chemotherapy has not been consistently observed.^[11] For instance, there was no statistically significant difference between calendula and an aqueous cream in breast cancer patients with radiation-induced dermatitis.

There are few high-quality clinical trials for calendula; therefore, it should be used with caution. There are few reports describing serious adverse reactions to calendula. However, allergic reactions and contact sensitization have been reported for other members of the daisy family (Asteraceae), to which calendula also belongs.^[12] Additionally, a clinical trial that studied the effect of calendula versus metronidazole on bacterial vaginosis reported a greater occurrence of vaginal itching with the calendula preparation.^[2]

Calendula’s anti-inflammatory effects are thought to come from its high flavonoid or antioxidant content.^[7] Its wound-healing effects may come from calendula's ability to enhance blood flow to the affected area, promoting healing and the generation of new tissue, which has been demonstrated in animal studies.^[8]