Synonyms and Common names: Harhound, Hoarhound, common hoarhound.
Description: White horehound is an erect mint-like plant, indigenous to Britain and widely distributed over Europe, central and northern Asia, and scattered throughout North America.
It is densely covered in white fur, has a thick stem, and grows up to 60cm. The circular to broadly ovate wrinkled leaves, 15-40mm long, are bluntly toothed at the margins. The upper surface is greyish and less hairy than the lower surface.
Dense whorls of off-white flowers, about 15mm long, are found in the axils of paired, leaf-like bracts The calyx tube has ten tiny hooked teeth at the rim. White horehound flowers between April and October and inhabits roadsides and waste places.
Parts used: Dried leaves and flowering tops.
Collection: During the flowering period between June and September.
Constituents: Sesquiterpene bitters (including marrubiin), Diterpene alcohols (marrubenol, marrubiol, peregrinol, vulgarol, phytol), flavonoids (apigenin, luteolin), small amounts of pyrrolidine alkaloids (betonicine, stachydrine), traces of volatile oil (containing alpha-pinene, sabine, camphene and p-cymol), alkaloids, ursolic and caffeic acid, tannins, saponin, mucilage, minerals (especially potassium), vitamin C, resins, wax, sterols,
Actions: Gentle stimulating expectorant, gentle circulatory stimulant, relaxant, antispasmodic, antiseptic, bitter digestive and hepatic tonic, a soothing tonic for the mucous membranes, vulnerary.
Indications: acute or chronic bronchitis, whooping cough, catarrh of the respiratory tract, anorexia, dyspepsia. Specifically indicated in bronchitis with a non-productive cough.
Therapeutics and Pharmacology: White horehound is indicated in bronchitis and chest colds, particularly congestive catarrhal conditions with a non-productive cough. It has also been used to treat whooping cough. Its action is to relax the smooth muscles of the bronchi whilst promoting mucus production and expectoration. The expectorant action, caused by the stimulation of mucus secretion by the lining of the respiratory tract, is attributed to White horehound and to the volatile oil. A hot infusion of the herb has a diaphoretic action, and it has been used in the past to reduce malarial fever.
The cold-infusion is a bitter tonic to the digestive system. The sesquiterpene bitters, marrubiin and premarrubiin, stimulate the flow of saliva and gastric juices, thereby stimulating the appetite. As marrubiin breaks down in the gut, it stimulates the secretion and flow of bile, thus aiding digestion.
White horehound has a traditional reputation for calming a nervous heart. In small amounts, it exhibits a normalising effect on irregular heartbeats, although high doses may cause arrhythmias. The volatile oil helps to dilate the arteries.
Caution: No contraindications are known, but very large doses are purgative. It should be avoided during pregnancy and lactation.
Preparation and Dosage:
Infusion: Pour a cup of boiling water over 1 teaspoonful of dried herb and leave to infuse for 10-15 minutes. Drink 3 times a day.
Tincture: Take 1-2 ml of the tincture in warm water, take three times a day.
Additional Comments: One of the oldest and most reliable cough remedies known, White Horehound has been used since the time of the Egyptian pharaohs. It is one of the bitter herbs ordained to be eaten at Passover supper by the Jews (the Hebrew word marrob means 'bitter juice').
Gerard recommended it for the bites of serpents and mad dogs.
The Navajo gave mothers a decoction of the root before and after childbirth.