The herb vervain is a common perennial wildflower in England, found growing at the edge of roads and in meadows. It has a long history of use in Celtic religious tradition, and has been used as medicine by many cultures. The leaf and flower are the parts used medicinally.
Like other bitter plants, vervain has been used to stimulate appetite and digestion. Other traditional uses include treating abdominal spasms, fevers, depression (especially following illness or childbirth), and inadequate flow of breast milk.
One study in rats found possible sedative effects with a vervain extract.1 A test-tube study found hints of potential anti-cancer effects.2 However, evidence like this is far, far too preliminary to show efficacy. Only double-blind, placebo-controlled studies can prove that a treatment really works, and no studies of this type have been performed on vervain. (For information on why such studies are essential, see Why Does This Database Rely on Double-blind Studies?)
A typical dosage of vervain is 2–3 grams three times daily, taken as dry herb or made into tea. Equivalent dosages are also available in tincture form, and may be more palatable.
Although vervain is thought to be a relatively safe herb, it has not undergone any meaningful safety testing at a modern scientific level. There is some reason to believe it may not be safe for use in pregnancy.3 Despite its reputation for enhancing flow of breast milk, safety in nursing women has also not been established. Additionally, safety in young children or people with severe liver or kidney disease remains unknown.
1. Akanmu MA, Honda K, Inoue S, et al. Hypnotic effects of total aqueous extracts of Vervain hastata (Verbenaceae) in rats. Psychiatry Clin Neurosci. 2002;56:309–10.
2. Dudai N, Weinstein Y, Krup M, et al. Citral is a new inducer of caspase-3 in tumor cell lines. Planta Med. 2005;71:484–8.
3. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-Care Professionals. London: The Pharmaceutical Press; 1996:263.
Last reviewed December 2015 by EBSCO CAM Review Board Last Updated: 12/15/2015