Horehound is best known as an agent used in cough and cold preparations. It is a perennial member of the Mint family, and has the characteristic square stems. It is an attractive plant to bees, and has sort of a musky odor when brushed. The leaves are covered with white hairs, giving the plant an overall wooly appearance. It has a menthol-like taste, and in the kitchen is used mainly as a flavoring for sweets and teas. It has been used as a substitute for hops in beer, and legend has it that this herb has anti-magical properties.
The leaves of horehound are used in tonics, liquers, and ales, and are made into expectorant and antiseptic cough drops. An infusion relaxes muscles and helps expel mucus, treating bronchitis, croup, and asthma. Contains the chemical Marrubiin which studies show has phlegm-loosening(expectorant) properties. It destroys intestinal worms and acts as a digestive and liver tonic and a laxative. The tea is used internally and externally for eczema and shingles. Its sedative action works in small amounts to control rapid heartbeats. A hot infusion helps to break fevers and treats malaria when quinine is ineffective. It helps heal skin lesions. The Navajo tribe gave mothers a root decoction before and after childbirth. Horehound's woolly leaves were once used to clean milk pails, and the dried flower remains floated on oil as candle wicks. Horehound is a helpful treatment for wheezing, bronchitis, bronchiectasis (a damaged air passage within the lung), bronchial asthma, nonproductive coughs, and whooping cough. Horehound apparently causes the secretion of a more fluid mucus, which is more readily cleared by coughing. As a bitter tonic, horehound increases the appetite and supports the function of the stomach. Horehound also acts to normalize heart rhythm, improving its regularity. Horehound is less commonly used as a decoction for skin conditions.
The primary chemical constituents of Horehound include essential oil (pinene, limonene, camphene), diterpene alcohols (marrubinol, marruciol, silareol), sterols, saponins, bitter lactone, alkaloids (betonicine, stachydine), tannin, mucilage, bitter principle (marrubin), and vitamin C. It has a relaxing effect on heart tissue and is used by some herbalists as a circulatory tonic to help lower blood pressure. It also acts on the hormonal system and will normalize heavy or scanty menstruation. Horehound is valuable in the treatment of bronchitis where there is a non-productive cough. It combines the action of relaxing the smooth muscles of the bronchus while promoting mucus production, and thus expectoration. This herb has been used in the treatment of whooping cough. The bitter action stimulates the flow and secretion of bile from the gall-bladder, thereby aiding digestion. Horehound has also been used externally to promote the healing of wounds, eczema, shingles and dog bites. The essential oils in Horehound help dilate the arteries and relieve lung congestion. The extreme bitterness helps drive away worms. Horehound increases circulation to the lungs, expels mucus, and cools infection.