Calendula Studies Ranked by Distance From an Infused Oil

Ten calendula studies are worth knowing, but the most useful way to read them is by how far each sits from a bottle of infused oil, because that distance decides what the result can tell you. We ordered them from closest to furthest. The honest summary: very little has been published on infused oil as applied to skin, most human trials used ointments, creams, sprays or defined extracts, and several results disagree. That is why we make no skin claims for our oil and point to the paperwork and the literature instead.

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Closest to an infused oil

1. Novkovic et al., 2005: which maceration gives the most carotene

A lab comparison of marigold flower oil extracts made by maceration (room temperature and 70 C) and percolation, in olive and sunflower oil. The highest carotene content, 57.5 mg per kg of oil (as beta-carotene), came from a 72-hour room-temperature maceration in olive oil at 1:5 by weight (Hemijska industrija). It tells you that method and carrier change what ends up in the oil. It does not tell you what any of that does for skin, we only had the abstract, and the colour measure is spectrophotometric and non-specific.

2. Cosmetic Ingredient Review, 2010: is calendula flower oil safe in cosmetics?

The CIR expert panel assessed calendula extract, flower, flower extract, flower oil and seed oil, and concluded they are safe in cosmetics at the practices and concentrations in its report. It found them not irritating, sensitizing or photosensitizing in animal or clinical tests, with possible mild eye irritation (Andersen et al., Int J Toxicol). Its 2001 predecessor had found the data insufficient (Int J Toxicol 2001), so the conclusion is recent and conditional. CIR's reference table lists flower oil at use levels of "up to 0.1%" (CIR quick reference), but we could not verify how CIR defines flower oil, so do not read that as a limit for an infused oil.

3. Lavagna 2001 and Carvalho 2016: the two studies with "oil" in the description

An Italian study (Lavagna et al., Farmaco) examined an oily extract of St John's wort and Calendula arvensis, a different species, on cesarean wounds; the abstract reports no results. A Brazilian trial of 32 diabetic foot ulcer patients (Carvalho et al., Rev Esc Enferm USP, 2016) tested laser alone and laser with calendula oil; the abstract's significant area reductions are for laser groups, with no separate calendula-oil result. Neither can be cited for an effect.

Human trials of other forms of calendula

4. Giostri et al., 2022: standardized extract on hand wounds

In 40 patients with hand wounds left to close on their own, a standardized calendula extract epithelialised in a mean of 8.6 days versus 13.2 days with mineral oil (Tissue Barriers; p < 0.05 as printed). The extract was proprietary, the comparator was mineral oil rather than a vehicle matched to the extract, and the trial was small. It is among the cleaner positives, and it still says nothing about an infused oil.

5. Panahi 2012 and Sharifi-Heris 2018: diaper dermatitis, and an olive-oil twist

In 66 infants, both a calendula ointment (1.5% extract per the EU assessment) and an aloe cream were followed by improvement, with fewer rash sites in the calendula group (P = 0.001), and no untreated or placebo group (Panahi et al., ScientificWorldJournal). In 73 children, 1.5% olive and 1.5% calendula ointments gave similar severity scores on days 3, 5 and 7 (Sharifi-Heris et al., Dermatol Ther, 2018). With no untreated arm, similar scores do not show that either works; diaper rash often settles by itself. A 2015 trial of 100 infants reported complete improvement within three days in 86% with a bentonite cream and 52% with a calendula cream (Mahmoudi et al., Indian J Med Res). Persistent diaper rash is a pediatrician's question.

6. Pommier et al., 2004: radiation skin reactions, breast cancer

The most-cited positive trial: 254 women, grade 2 or higher dermatitis in 41% with a calendula ointment versus 63% with trolamine (P<.001); the comparator was not a placebo, and the ointment was a petroleum-jelly preparation made from aerial parts, not flowers alone (J Clin Oncol).

7. Sharp et al., 2013: the blinded trial that did not reproduce it

Among 411 women analysed, severe reactions occurred in 23% using a calendula cream and 19% using a standard cream, with no significant difference (Eur J Oncol Nurs). An Australian trial of 81 analysed women, underpowered at under half its target, also found no significant difference (Siddiquee et al., 2021), and the Oncology Nursing Society's 2020 guideline suggests against calendula for this use (Gosselin et al.). Anyone on radiotherapy should follow their radiation team's skin protocol.

8. Puaratanaarunkon et al., 2022: mask-related acne, a three-ingredient serum

In 66 people over 12 weeks, a serum combining snail secretion filtrate, calendula and licorice extract was followed by a greater fall in inflammatory lesions than placebo in the mask-covered area (p=0.03), but not in non-inflammatory lesions (J Cosmet Dermatol). Calendula's share cannot be separated. It is the only acne trial involving calendula that the evidence we reviewed turned up.

Further away: isolated compounds and a different question

9. Zitterl-Eglseer et al., 1997: faradiol esters in mouse ears

Faradiol myristate and palmitate isolated from marigold flower heads reduced croton-oil-induced ear swelling in mice; the free alcohol faradiol was more active than its esters (J Ethnopharmacol; abstract only). This is the usual source for "calendula is anti-inflammatory." It was isolated compounds in an acute mouse model, and a 2025 paper found these esters concentrated in ray florets at about 12-13 mg per g dry weight (Golubova et al., Nat Commun). Nothing we read measures how much of them ends up in an infused oil.

10. Reider et al., 2001: not efficacy at all, but allergy

In 443 dermatitis patients patch-tested in Austria, about 2% (9 patients) reacted to marigold (Contact Dermatitis). These were referred clinic patients, and the EU assessor discounted it because whole aerial parts were tested, not petals alone. It earns a place because it is the only calendula-specific patch-test rate we could verify.

Reading the pile

Put together, the ten studies support a narrow statement: calendula preparations have been tested in human trials in several forms, results range from encouraging to null, the EU herbal committee judged the clinical evidence insufficient for more than traditional use (EMA/HMPC, 2018), and no trial we found tested an infused oil on a skin outcome. What we can speak to firsthand is the flower, the drying, the infusion and the batch documentation, which you can request by emailing a lot number to [email protected]. For wounds see our wound studies article, for sun see SPF, and for the myths built on these studies see calendula oil myths.

If you are allergic to daisy-family plants, none of this is a reason to try it.

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Sources & Further Reading