Achillea millefolium

Specific Indications. - Atony and relaxation of tissue, with free discharges; passive hemorrhage.

Action and Therapy. - Achillea is astringent and tonic. Its chief virtues are shown in its occasional control of passive menorrhagia due wholly to atony, and not to the presence of tissue change or destruction. It sometimes relieves hematuria, and is soothing to the urinary tract.

The Eclectic Materia Medica, Pharmacology and Therapeutics by Harvey Wickes Felter, M.D. (1922)

Herbal medicine

Yarrow has seen historical use as a medicine, often because of its astringent effects. Decoctions have been used to treat inflammations such as piles (hemorrhoids), and also headaches. Confusingly, it has been said to both stop bleeding and promote it. Infusions of yarrow, taken either internally or externally, are said to speed recovery from severe bruising. The most medicinally active part of the plant are the flowering tops. They also have a mild stimulant effect, and have been used as a snuff. Today, yarrow is valued mainly for its action in colds and influenza, and also for its effect on the circulatory, digestive, excretory, and urinary systems. In the nineteenth century, yarrow was said to have a greater number of indications than any other herb.