Herb & supplement monograph

Yarrow Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Yarrow interacts with medications. The heart of this page is the interaction list — every drug Yarrow is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Yarrow is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Yarrow Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Yarrow drug interaction appears low for most people. Only one medication interaction is documented for yarrow, it is rated moderate rather than major, and it rests largely on animal research.

Interactions deserving the most attention

The one combination that deserves real attention is lithium. Animal research suggests yarrow may act as a diuretic, and anything that changes how the body removes water can also slow the removal of lithium, letting its levels climb. Because lithium is a narrow-margin medicine where even small level changes can cause side effects, anyone taking it should talk with their prescriber before adding yarrow, since the lithium dose sometimes needs adjusting in situations like this.

What the rest of the list means

Beyond lithium, yarrow has an unusually short interaction record for an herbal supplement, which is reassuring. Keep in mind that even the lithium concern is theoretical at this stage, predicted from yarrow's possible diuretic effect in animals rather than confirmed by human studies. A short list also reflects limited research, so caution with closely monitored medicines is still sensible.

Check your medications against Yarrow

Based on HelloPharmacist’s Yarrow interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Yarrow

1 medication has a known interaction with Yarrow, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Yarrow using our pharmacist-reviewed interaction data.

AI summaries are generated from our Yarrow interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Lithium Carbonate (prescription Drug)Eskalith, Lithium Carbonate

Moderate Lithium

Theoretically, taking yarrow with lithium might increase the levels and adverse effects of lithium.

Read the full Yarrow + Lithium Carbonate (prescription Drug) interaction Lithium Carbonate (prescription Drug) drug page: uses, dosage & side effects

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Yarrow combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Yarrow affects

Every type of medication (drug category) Yarrow is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 1 drug category Yarrow interacts with

Lithium

Theoretically, taking yarrow with lithium might increase the levels and adverse effects of lithium.
Animal research shows that yarrow has diuretic activity. Theoretically, due to these potential diuretic effects, yarrow might reduce excretion and increase levels of lithium. The dose of lithium might need to be decreased.

Likelihood Probable Evidence D

Monograph

Yarrow: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Yarrow is a traditional herb long used for wounds, digestive complaints, and colds, but high-quality human studies are very limited, so its benefits are not well proven. It is generally used short-term, and people who are pregnant, breastfeeding, or allergic to ragweed and related plants should avoid it.

Scientific name: Achillea millefolium
Family: Asteraceae
Part used: Aerial parts (leaves, flowers, and stems) and essential oil
Common forms: Tea, tincture, capsules, dried herb, topical creams or ointments, and essential oil

People commonly use it for

Wounds and minor bleeding
Digestive upset and cramping
Colds, flu, and fever
Skin conditions
Menstrual discomfort

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Often used short-term, but human safety data are limited and allergic reactions can occur.

PregnancyLikely Unsafe

When used orally; yarrow is believed to be an abortifacient and affect the menstrual cycle.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid use.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Yarrow (Achillea millefolium) is a flowering perennial herb in the daisy family. It grows wild across Europe, Asia, and North America and is known for its feathery leaves and clusters of small white or pale pink flowers.

People have used yarrow in folk medicine for centuries. The leaves, flowers, and stems are dried for teas and tinctures or made into creams and oils. Traditionally it was applied to cuts to slow bleeding, taken for stomach complaints, and used to support sweating during colds and fevers.

How it works

Yarrow contains a mix of plant compounds, including flavonoids, tannins, volatile oils (such as chamazulene), and sesquiterpene lactones. In laboratory studies, some of these compounds appear to reduce inflammation, fight certain bacteria, and act as antioxidants.

Its traditional use for bleeding may relate to compounds that affect blood clotting and to its astringent tannins, which can tighten tissue. Bitter compounds may stimulate digestion. Keep in mind that most of these mechanisms are based on test-tube or animal research, and what happens in the body of a person taking yarrow is not fully understood.

Effectiveness

Does Yarrow work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 10 uses evaluated

10 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Yarrow, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 10 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Atopic dermatitis (eczema)