Yarrow (Achillea millefolium) has a long history of use in traditional herbal medicine, particularly for women’s health concerns such as menstrual irregularity, heavy menstrual bleeding, and menstrual cramps. In European and Western herbal traditions, yarrow tea or extracts were often recommended to “regulate the menses” and alleviate symptoms of dysmenorrhea (painful periods). The herb is believed to have mild antispasmodic and astringent properties, which may help reduce excessive menstrual bleeding and ease uterine muscle spasms associated with irregular or painful periods.

The evidence for yarrow’s effectiveness in treating menstrual irregularity, however, is primarily anecdotal and derived from centuries of traditional use rather than robust clinical research. Few scientific studies have directly evaluated yarrow for this specific indication. Some laboratory research has demonstrated that yarrow contains flavonoids, alkaloids, and volatile oils with potential anti-inflammatory and muscle-relaxant effects, which could plausibly influence menstrual symptoms. Nonetheless, high-quality clinical trials in humans are lacking, so the efficacy and safety profile for this use remain uncertain.

In summary, yarrow’s use for menstrual irregularity is justified mainly by tradition, with a moderate historical reputation but limited scientific validation. Those interested in trying yarrow should consult a healthcare provider, especially if taking other medications or managing underlying health conditions.