# Licorice (Glycyrrhiza glabra)

**Glycyrrhiza*, “sweet root”; the Scythian root*

**Known today as.** The root of *Glycyrrhiza glabra*.

Kind: Plant

> **Caution.** Large or daily amounts raise blood pressure and lower potassium.

## What was it used for?

For coughs, hoarseness, and the chest, and to sweeten bitter medicines.

## What does modern science say?

Glycyrrhizin soothes the throat, but in quantity it raises blood pressure and lowers potassium. Glycyrrhizin is fifty times sweeter than sugar and mimics the hormone that holds salt; a bag of licorice sweets a day can raise the blood pressure and drop the potassium far enough to stop the heart, and the United States Food and Drug Administration warned of it in 2017. A licorice extract stripped of glycyrrhizin is used for stomach ulcers.

## Pharmacognosy and toxicology

- **glycyrrhizin**: 
- **glycyrrhetinic acid**: its active metabolite
- **glabridin**: 

**Mechanism.** Glycyrrhetinic acid blocks the enzyme that keeps cortisol from the kidney’s mineralocorticoid receptor, so the kidney retains salt and loses potassium.

**Dose.** Above about 100 mg of glycyrrhizin a day, which 50 g of sweets can hold, blood pressure rises and potassium falls; deaths from heart rhythm are recorded.

**Standing.** Approved in Europe as a traditional remedy for the chest and stomach; the FDA warned in 2017 against more than two ounces a day of black liquorice in those over forty.

## What lore surrounds it?

Dominican friars are said to have brought the plant to Pontefract in Yorkshire, where the root grew in the castle grounds, and Pontefract cakes, stamped with the castle, were made from 1614; the sweet “Spanish” of the English north was licorice stick. Napoleon chewed it, and his blackened teeth were put down to it.

## What did the older authorities say?

**Theophrastus.** Says the Scythians could go eleven or twelve days without drinking by eating this root.

**The Egyptians.** Buried a store of licorice root in the tomb of Tutankhamun, and drank a sweet licorice water, *mai sus*, still sold in the streets of Cairo.

**Dioscorides.** Gives the juice of the root for the chest, the throat, and the burning of the stomach, and says it quenches thirst, as Theophrastus had said of the Scythians.

## Sources

- Theophrastus, *Enquiry into Plants* IX.
- Omar, H. R., et al. (2012). “Licorice abuse: time to send a warning message.” *Therapeutic Advances in Endocrinology and Metabolism* 3.
- Omar, H. R., et al. (2012). *Therapeutic Advances in Endocrinology and Metabolism* 3.

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

Historical description, not medical advice.