HERBS: Licorice

Scientific name
Other names
Food sources
Purported uses
Warnings
Contraindications
Adverse reactions
Drug interactions
References

Licorice

Scientific name

Glycyrrhiza glabra, Glycyrrhiza uralensis

Other names

Gan cao, sweet root, glycyrrhiza, Radix liquiritiae, liquorice

Food sources

Flavoring agent.

Purported uses

To treat bronchitis and chest congestion: No scientific evidence supports this use.
To relieve constipation: No scientific evidence supports this use.
To treat gastrointestinal disorders such as peptic ulcers: A substance in licorice called carbenoxolone has shown positive effects in patients with peptic ulcers.
To treat hepatitis: Clinical trials in Japan have used a licorice extract (containing glycyrrhizin) to treat hepatitis B and C, with positive effects, but there is no proof that deglycyrrhizinated licorice has the same effects.
To reduce inflammation: Studies in animals support this use, but there is no proof from clinical trials that�this effect occurs in humans.
To relieve menopausal symptoms: Studies in animals show that licorice has estrogenic effects, but there is no proof from clinical trials that�this effect occurs in humans.
To treat microbial infections: Studies in animals suggest that licorice has anti-microbial activity, but there is no proof from clinical trials that�this effect occurs in humans.
To treat primary adrenocortical insufficiency: Studies in animals do not support this use.
To treat prostate cancer: No scientific evidence supports this use. Licorice is an ingedient in�PC-SPES.

Warnings

Due to the adverse reaction profile of licorice, many studies have been performed using the deglycyrrhizinated licorice (DGL) extract. Deglycyrrhizinated licorice is free of glycyrrhizin and has had no reported significant adverse effects.

Contraindications

Licorice should not be consumed by those with renal or liver dysfunction, or women who are pregnant or breast-feeding.

Adverse reactions

Hypertension, lethargy, muscle pain, cardiac arrhythmias, sodium retention, hypokalemia, hyper-mineralcorticoidism, pseudo-hyperaldosteronism, decreased libido in men, and suppression of scalp sebum secretion

Drug interactions

Cardiac glycosides: Licorice may potentiate toxicity.
Stimulant laxatives: Chronic use of licorice may increase loss of potassium.
Diuretics: Chronic use of licorice may increase loss of potassium.
Spironolactone / Amiloride: Licorice should not be used simultaneously due to effects on sodium and potassium excretion.
Corticosteroids: Concomitant use with licorice might potentiate the duration of activity.
Aspirin: Licorice may reduce ulcer formation from aspirin and possibly provide protection from gastric mucosal damage.
Insulin: Licorice may have a synergistic effect possibly causing hypokalemia and sodium retention with concomitant use.
Hormonal therapy: Licorice may interfere with the activity of hormonal therapy due to its estrogenic or anti-estrogenic properties.
Anticoagulant/Antiplatelet Drugs: Licorice may potentiate activity due to coumarin constituent.
MAO-inhibitors (MAO-I): Licorice may potentiate activity of MAO-Is.

References

1. Blumenthal, et al. Herbal Medicine, Expanded Commission E Monographs. Austin: American Botanical Council; 2000.

2. Newall C, et al. Herbal Medicines: A Guide for Health-Care Professionals. London: Pharmaceutical Press; 1996.

3. Tyler V. Herbs of Choice, the Therapeutical Use of Phytomedicinals. Binghamton: Pharmaceutical Press; 1994.

4. Schulz V, et al. Rational Phytotherapy: A Physicians Guide to the Use of Herbs and Related Remedies, 3rd ed. Berlin (Germany): Springer; 1998.

5. Takahara T, Watanabe A, Shiraki K. Effects of glycyrrhizin on hepatitis B surface antigen: a biochemical and morphological study. J Hepatol 1994;21:601-9.

6. De Smet K, et al. Adverse Effects of Herbal Drugs, Vol 3. New York: Springer; 1997.

7. Miyamura M, et al. Properties of glycyrrhizin in Kampo extracts including licorice root and changes in the blood concentration of glycyrrhetic acid after oral administration of Kampo extracts. Yakugaku Zasshi 1996;116:209-16.

8. Ichikawa T, et al. Biliary excretion and enterohepatic cycling of glycrrhizin in rats. J Pharm Sci 1986;75:672-5.

9. Stormer FC, Reistad R, Alexander J. Glycyrrhizic acid in licorice - evaluation of health hazard. Food Chem Toxicol 1993;31:303-12.

10. Brinker F. Herb Contraindications and Drug Interactions, 2nd ed. Sandy (OR): Eclectic Medical Publications;1998.

11. Amato P, Christophe S, Mellon PL. Estrogenic activity of herbs commonly used as remedies for menopausal symptoms. Menopause 2002;9:145-50.

12. Budzinski JW, et al. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82.

13. Lin SH. An unusual cause of hypokalemic paralysis: chronic licorice ingestion. Am J Med Sci 2003 Mar;325(3):153-6.