The leaves and flower tops of the horehound have long been used in home remedies for the common cold. They are now used primarily as flavorings in liqueurs, candies, and cough drops. Extracts of the plant have also been used for treating intestinal parasites, as a diaphoretic, and as a diuretic.

The active ingredients are obtained from the leaves and flowers of M. vulgare. Horehound's active compound, marrubi in, stimulates secretions in the bronchioles and works as an expectorant. It also contains antiarrhythmic properties, but is of limited use for this purpose because large doses can also cause arrhythmias.

Marrubin acid, derived from marrubiin, stimulates bile secretion. An aqueous extract from horehound may have antagonistic activities toward serotonin. The horehound extract has hypoglycemic effects. Horehound is available as dried herb, liquid extract, lozenges, powder, syrup, and tea.