Yarrow

What is yarrow?

Yarrow (Achillea millefolium) is a flowering plant in the daisy (Asteraceae) family, recognizable by its flat clusters of small white or pink flowers and feathery leaves. It is one of the oldest known medicinal plants; its genus name refers to the Greek hero Achilles, who according to legend used it to treat soldiers’ wounds. Traditional uses across Europe and Asia include spasmodic digestive complaints, liver and gallbladder problems, menstrual complaints, inflammation and wound healing.

What the research says

A 2017 review of yarrow’s pharmacology describes a wide range of compounds, especially monoterpenes in the essential oil, along with flavonoids and sesquiterpene lactones. Lab and animal experiments suggest anti-inflammatory, antiulcer and antioxidant activities, which the authors say support the rationale behind its traditional uses. However, this evidence comes mostly from experimental models rather than from controlled clinical trials in people.

A 2023 review focused on pharmacokinetics and drug interactions adds an important safety angle. It discusses how yarrow may affect cytochrome P450 liver enzymes, potentially raising the levels of drugs such as erythromycin, diazepam and cyclosporine, and it categorizes potential interactions with hormonal, antibiotic and anticancer drugs.

Oral health. Yarrow’s traditional reputation for wound healing and inflammation is sometimes cited for gums, but we found no clinical trials showing that swallowing yarrow improves gum health, plaque or breath.

How it’s used in supplements

Yarrow is used in herbal teas, tinctures and capsules, and occasionally in topical products. There is no well-established effective oral dose from clinical research. In combination supplements it often appears in small amounts, such as 50 mg, which is unlikely to have a measurable effect.

Because yarrow is in the daisy family, people allergic to ragweed, chrysanthemums, marigolds or daisies may react to it, including with skin rashes. Yarrow has traditionally been considered unsuitable during pregnancy, and it should be avoided by pregnant or breastfeeding women. Given the possible enzyme interactions described above, anyone taking prescription medications, particularly those with a narrow safety margin such as cyclosporine, should talk to a doctor or pharmacist before using yarrow-containing products. People scheduled for surgery should tell their surgeon about any herbal supplements they take.

Overall, yarrow is an herb with a long folk history and interesting laboratory findings, but without human trials that define a useful dose or confirm benefits. For gum inflammation specifically, the proven approaches are removing plaque through brushing, cleaning between teeth and professional cleanings, and seeing a dentist if bleeding persists.