# Horehound (Marrubium vulgare)

**Marrubio**

**Known today as.** White horehound, *Marrubium vulgare*.

Kind: Plant

## What did Canale use it for?

In the oil; among the amulets (chs. 9–10).

## What does modern science say?

A traditional expectorant, recognized by European regulators on the strength of long use rather than clinical trials; still found in cough sweets. Marrubiin, its bitter principle, stimulates the secretions of the bronchi and the appetite; Germany’s Commission E approves the herb for coughs and loss of appetite on the strength of tradition, and it flavours lozenges from Ricola to the horehound drops of New England.

## Pharmacognosy and toxicology

- **marrubiin**: a diterpene lactone bitter, 0.3–1 per cent
- **premarrubiin**: its precursor
- **marrubenol**: 
- **caffeoylquinic acids**: 

**Mechanism.** Marrubiin is a bitter that raises gastric secretion and is expectorant by the saponin-like vagal route; marrubenol relaxes vascular muscle through calcium channels in animal work and lowers blood pressure in rats.

**Dose.** Safe at tea and lozenge doses; large doses of the juice disturb the heart rhythm in animals.

**Standing.** EMA monograph (2013) for coughs and colds and mild dyspepsia; the standard flavour of American cough drops.

## What lore surrounds it?

Its English name is from the Old English *hār hūne*, the hoary plant, for the white down on its leaves; “hound” is folk etymology. Horehound candy, boiled from the decoction with sugar, was sold in every American drugstore into the twentieth century and still is in some.

## What did the older authorities say?

**Celsus.** Gives horehound for the chest in the first century, and Columella for worms in cattle; Pliny says the Egyptian priests prized it, and it was one of the bitter herbs of Passover by some accounts.

**Gerard.** Writes that a syrup of the green leaves and sugar is “a most singular remedie against the cough and wheesing of the lungs.”

## Sources

- Grieve, M. *A Modern Herbal*, “Horehound, White.” As published on botanical.com.
- Celsus, *De medicina* IV.
- Gerard, J. (1597). *The Herball*.
- EMA/HMPC (2013). *Community herbal monograph on Marrubium vulgare L., herba* (EMA/HMPC/604271/2012).
- El Bardai, S., et al. (2003). “The vasorelaxant activity of marrubenol and marrubiin from *Marrubium vulgare*.” *Planta Medica* 69.

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*Horehound.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-01. The Thinking Press. https://thethinkingpress.org/materia-medica/horehound

Historical description, not medical advice.