Glycyrrhiza: Licorice and hypertension

by Paul Bergner

Medical Herbalism 10(4):15

A twenty-five year old woman, 5’ 5" tall, and weighing 108 lbs, took two herbal decoctions, each containing licorice root, daily for approximately three months. The total consumption of licorice root tea was approximately eight ounces of decoction per day, with an unspecified amount of the root by weight. After the three months, she developed a persistent diastolic blood pressure between 90 and 95 mm Hg., with a systolic pressure above 140. Within ten days of ceasing the licorice, the blood pressure returned to her normal between 110 and 120 systolic and 70-80 diastolic pressure. She had no previous history of hypertension.

Large doses of licorice extract, usually in the form of candy or chewing gum, may cause hypertension and electrolyte imbalances, according to several reports in the scientific literature, and the supposed mechanism is well-defined (de Klerk). A mineral corticoid effect of licorice constituents was described in the literature as long ago as 1950 (Molhuyssen et al.) Estrogens may enhance the mineral corticoid effect of the licorice constituent glycyrrhetic acid, which may explain why female sex and the use of oral contraceptives can increase the susceptibility to adverse reactions to licorice (Bernardi et al.). The woman above was not taking exogenous estrogen. Zhu states that continuous use or high doses of licorice lead to hypertension and sodium retention in approximately 20% of patients (Zhu). The effect is well-known when licorice is used chronically to treat peptic ulcer, and licorice extracts with the glycyrrhizin removed are now routinely used for that condition. This is the first report we are aware of in which dosage and duration of a decoction of licorice which can produced the effect are specified.

Bernardi M, D’Intino PE, Trevisani F, Cantelli-Forti G, Raggi MA, Turchetto E, et al. Effects of prolonged ingestion of graded doses of liquorice by healthy volunteers. Life Sci 1994;55:863-72.

de Klerk G.J., Nieuwenhuis M.G., Beutler, J.J. Hypokalaemia and hypertension associated with use of liquorice flavoured chewing gum. BMJ 1997;314:731 (8 March)

Molhuysen JA, Gerbrandy J, de Vries LA, de Jong JC, Lenstra JB, Turner KP, Borst JGT. A liquorice extract with deoxycortone-like action. Lancet 1950;ii:381-6.

Zhu, You-Ping. Chinese Materia Medica: Chemistry, Pharmacology, and Applications. Harwood Academic Publishers, 1998
Copyright 2001 Paul Bergner

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