Question 1

How does yarrow work to stop bleeding?

Accepted Answer

Yarrow contains achillin and flavonoids that promote blood clotting through vasoconstriction and platelet aggregation. The herb's hemostatic action comes from volatile oils, particularly chamazulene and camphor, which constrict blood vessels at wound sites. These compounds work together to slow bleeding and support the body's natural clotting cascade. Traditional use spans centuries, with Level B evidence supporting wound-healing properties. The plant was historically called 'herba militaris' by Roman soldiers who carried it into battle.

Question 2

Does yarrow interact with blood thinners or medications?

Accepted Answer

Yarrow may interact with anticoagulant and antiplatelet medications such as warfarin, aspirin, and clopidogrel due to its effects on blood clotting. The herb's hemostatic properties could theoretically counteract blood-thinning medications. Yarrow may also enhance sedative effects and affect lithium levels in the body. Patients on blood thinners, sedatives, or lithium should consult a healthcare provider before using yarrow. Avoid combining with other herbs that affect clotting without medical supervision (Evidence Level B).

Question 3

What is the recommended dosage for yarrow tea or tincture?

Accepted Answer

For adults, the standard dosage is 2-4 grams of dried yarrow herb prepared as tea, or 3-5ml of tincture taken up to three times daily. Steep dried herb in boiling water for 10-15 minutes to prepare tea. Dosage for children has not been established. Do not exceed recommended amounts. Consult a qualified herbalist or healthcare provider for personalized guidance, especially if taking other medications (Evidence Level B, Traditional).

Question 4

Is yarrow safe to take during pregnancy?

Accepted Answer

Yarrow is unsafe during pregnancy and should be strictly avoided. The herb has emmenagogue properties, meaning it stimulates uterine contractions and menstrual flow, which may cause miscarriage or premature labor. Norse yarrow was traditionally used to regulate menstruation, underscoring its effects on the reproductive system. Women who are pregnant, trying to conceive, or breastfeeding should not use yarrow in any form. No safe threshold has been established for pregnancy use (Evidence Level B, Traditional).

Question 5

What did Vikings use yarrow for?

Accepted Answer

Vikings and Norse peoples used yarrow primarily as a wound herb to staunch bleeding on the battlefield and in daily life. They also employed it as a digestive bitter to stimulate appetite and improve digestion, and as a remedy for fevers and colds. The Nordic variety (Achillea millefolium var. borealis) was valued for its hardiness in cold climates. Modern herbalists continue these traditional applications with Level B evidence supporting wound-healing and anti-inflammatory properties.

Question 6

Can yarrow cause allergic reactions?

Accepted Answer

Yes, yarrow can cause allergic reactions, particularly in individuals sensitive to plants in the Asteraceae family, which includes ragweed, chrysanthemums, and marigolds. Contact dermatitis may occur with topical application, appearing as red, itchy skin. Internal use may trigger allergic responses in susceptible individuals. Photosensitivity has also been reported. Those with known Asteraceae allergies should avoid yarrow entirely. Discontinue use immediately if rash, itching, or other allergic symptoms develop (Evidence Level B, Traditional).

Norse Yarrow

Sources & Citations

Yarrow Yellow

Thyme

Nordic Yarrow

Summary

Background

Traditional uses

Active compounds

Mechanism of action

Clinical evidence

Evidence summary

PubMed sources

Government sources