Horehound
Scientific Name(s): Marrubium vulgare (Tourn.) L.
Common Name(s): Hoarhound, Horehound, Maromba, Marroio, White horehound
Medically reviewed by Drugs.com. Last updated on Jul 22, 2021.
Clinical Overview
Use
Clinical studies regarding therapeutic uses of horehound are limited. Research has centered on the potential for use in cardiovascular disease, diabetes, and pain and inflammation; however, no clinical evidence supports the use of horehound in these roles or in cough preparations.
Dosing
Clinical trials are lacking to provide dosing guidance. One clinical study evaluating the effect of horehound in type 2 diabetes used horehound infusions prepared with the leaves of M. vulgare and administered in 1 g envelopes, 3 times a day for 21 days.
Dosages of 4.5 g daily as the crude herb and 30 to 60 mL as pressed juice from the herb have been traditionally used.
Contraindications
Use in pregnancy is contraindicated.
Pregnancy/Lactation
Avoid use. Horehound reportedly has emmenagogue and abortifacient effects.
Interactions
None well documented.
Adverse Reactions
In a small clinical study, nausea, dry mouth, excessive salivation, dizziness, and anorexia were reported by some patients drinking a prepared infusion solution of dry leaves of the plant.
Toxicology
Marrubiin, one of the main constituents of M. vulgare, has a median lethal dose (LD50) of 370 mg/kg when administered orally to rats and an LD50 of 100 mg/kg when injected in mice; marrubiin was not cytotoxic to any of 66 cell lines tested. M. vulgare was given to rats at increasing doses of up to 1,000 mg/kg daily for 3 weeks, with no signs of toxicity. As a flavoring agent and essential oil, horehound has been granted generally recognized as safe (GRAS) status by the US Food and Drug Administration (FDA).
Scientific Family
- Labiatae (mint)
- Laminaceae
Botany
Horehound is native to Europe and Asia and has been naturalized to other areas, including the United States.1 It is a perennial, aromatic herb of the mint family. The plant grows to a height of approximately 1 m, and has oval leaves covered with white, woolly hairs. Horehound bears small, white flowers in dense whorls, which bloom from June to August.12, 3
History
The leaves and flower tops of the horehound plant have been traditionally used in the form of a bitter tonic as a home remedy for the common cold. Horehound is now primarily used to flavor liqueurs, candies, and cough drops.4 Although there is no evidence to support use in cough preparations,2, 3 the FDA has granted horehound GRAS status when consumed at concentrations used in such preparations.5 Traditional uses of plant extracts include treatment of intestinal parasites; as a diaphoretic, diuretic, and digestive aid, and appetite stimulant; and in cancer.3, 6 An unrelated species, the black horehound (Ballota nigra), is a fetid-scented perennial native to the Mediterranean region that is sometimes used as an adulterant of white horehound.2
Chemistry
Horehound contains 0.3% to 1% of the bitter principle marrubiin (a diterpene lactone); several diterpene alcohols (eg, marrubiol, marrubenol); and marrubiinic and marrubic acids. Phenylpropanoid esters and glycosides, as well as a phenylethanoid glycoside (marruboside) have been isolated from the aerial parts.
