Square-stemmed perennial growing to about 20 in (50 cm). Has toothed, downy leaves and double-lipped white flowers.
Habitat & Cultivation
Native to Europe, white horehound is naturalized in North and South America. It flourishes in dry, bare, or open areas, and is gathered in spring.
White horehound contains the diterpenes marrubiin (0.3–1.0%) and marrubenol, tannins, and 0.06% volatile oil. Marrubiin is thought to be chiefly responsible for the herb’s expectorant and bitter activity. It also acts on the heart to correct an irregular heartbeat.
History & Folklore
White horehound has been a remedy for chest problems since ancient times, perhaps most frequently taken as a syrup made with honey or sugar. The Greek physician Dioscorides (40–90 CE) recommended a decoction of white horehound as a treatment for tuberculosis, asthma, and coughs.
Medicinal Actions & Uses
White horehound is helpful for wheeziness, bronchitis, bronchiectasis (a damaged air passage within the lung), bronchial asthma, non-productive coughs, and whooping cough. The herb apparently causes the secretion of a more fluid mucus, which is readily cleared by coughing.
As a bitter tonic, white horehound increases the appetite and supports the function of the stomach. It is widely used in Mexico to help control type 2 diabetes. The herb may also act to normalize heart rhythm, improving its regularity.