Yarrow

What It Is

Yarrow (Achillea millefolium) is a perennial medicinal plant from the Asteraceae family, long used in European, Middle Eastern, and Indigenous North American herbal medicine. Virtually all aerial parts — flowers, stems, and leaves — are used. It can be taken internally (tea, tincture, capsules) or applied topically (poultices, salves, compresses, hydrosol).

How It Works

Yarrow expresses several pharmacologic “clusters” of action:

• Hemostatic & astringent — Tannins and alkaloids cause local vasoconstriction and tissue-tightening, helping slow or stop bleeding and weepiness (topical or internal).

• Anti-inflammatory & vulnerary (wound-healing) — Sesquiterpene lactones and flavonoids temper inflammatory cascades and support granulation tissue.

• Antispasmodic & carminative — Volatile oils relax smooth muscle in the gut and bile ducts, aiding spasm, gas, and sluggish digestion.

• Diaphoretic — It promotes an “even” sweat, historically used during febrile states to assist temperature regulation and viral convalescence.

• Antimicrobial — Multiple constituents have mild antibacterial and antifungal activity, relevant to topical use.

• Circulatory modulation — Warming/vasodilating in some contexts (peripheral microcirculation), tightening/hemostatic in others; the overall effect is context-sensitive to route and dose.

Why It’s Important

Yarrow is valued because it spans acute first-aid and chronic modulation with a gentle safety profile when used appropriately. Its ability to both close and cool wounds externally, yet open peripheral circulation and resolve stagnation internally, makes it unusually versatile. It historically served as a rural “mini-formulary” herb: one plant covering wound care, fever management, digestive spasm, and menstrual balance. In the contemporary context it remains relevant as a low-tech, low-cost, rapidly deployable botanical for minor injuries, seasonal viral illness support, and functional digestive or menstrual discomfort.

Considerations

• Internal bleeding and pregnancy — Avoid or use only with qualified guidance; the uterine-active and hemostatic actions make high or prolonged doses inappropriate in pregnancy, and yarrow should not be used to manage unexplained internal bleeding without medical care.

• Asteraceae allergy — As a composite family plant, it can provoke reactions in individuals sensitive to ragweed/chamomile family.

• Drug interactions — Theoretically additive with other hemostatics or anticoagulants; also mild CYP modulation has been reported in vitro though evidence is not robust — caution is prudent with narrow-therapeutic-index drugs.

• Duration and dose — Botanicals with sesquiterpene lactones can irritate gastric mucosa in susceptible people at higher doses or long courses; pulse dosing or topical route can reduce exposure.

• Appropriate scope — Yarrow is for minor, non-complicated use; do not rely on it for serious trauma, systemic infection, high-risk pregnancy, GI bleeding, or undiagnosed fever in vulnerable populations.