Medical Attributes of Glycyrrhiza glabra – Licorice
John Treven, Steve Lehmkuhl, and Jonelle Vinton
Wilkes University, Wilke-Barre,
glabra, commonly called licorice, is a member of the Fabaceae
(legume family). G. glabra
is native to the Mediterranean region and central and southwest
Asia. It was introduced to Europe in the fifteenth century where
the roots became popular chewing sticks (Kowalchik & Hylton, 1987;
Brown, 1995). Two other commonly used relatives include Glycyrrhiza lepidota which is found
throughout America and Glycyrrhiza
uralensis which is found in northwest China (Foster, 2000).
G. glabra root was used during
the time of the Roman Empire and was also found in the first Chinese
herbal (Kowalchik & Hylton, 1987). Hippocrates, Theophrastus,
and Pliny where aware of the therapeutic value of the root and it was
used to soothe throats and quench thirst. Theophrastus mentioned
it in his Inquiry into Plants for asthma and wound healing.
Today, licorice root is used to flavor and color beverages and is also
used to flavor tobacco products. Medicinally, it has been used for
treatment of dropsy; fever; menstrual cramps; menopause symptoms;
irritated urinary, bowel, or respiratory passages; influenza; and
hypoglycemia. It has also been used as a diuretic, demulcent,
expectorant, emollient, antispasmodic, mild laxative, and cough remedy
(Kowalchik & Hylton, 1987).
The most common medicinal use for licorice root is as a treatment for
irritated skin with symptoms such as dermatitis, eczema, pruritus and
cysts (Saeedi, Morteza-Semnani & Ghoreishi, 2003). G. glabra had remarkable effects
against certain bacteria that cause acne, and greater results than
erythromycin which is marketed for acne treatment (Nam, et al, 2003).
Licorice root has also been used in the past as an expectorant, meaning
it loosens and helps expel congestion in the upper respiratory tract
(Foster, 2000). G. glabra has
a history of being used to treat ulcers dating back to 1942. Current
studies show it encourages mucus secretion and promotes life span of
surface cells in the stomach. The combined effect of these leads to
reduction of gastric ulcers (Foster, 2000).
The main ingredient in the root is a saponin like glycoside called
glycyrrhizin. It is more than fifty times sweeter than sugar and
is used to enhance chocolate. It has recently been identified as
a selective inhibitor of thrombin. However, it does not inhibit the
blood clotting action of thrombin meaning that the interaction is not
very intense. The anti-inflammatory effect of glycyrrhizin may be due
to its anti-thrombin properties (Francischetti, Monterio &
Other medical uses of licorice root have been tested. As an anti-cancer
agent, glycyrrhizin has shown to offer protection from cancerous damage
produced by humans or UVB radiation, but not useful as a treatment for
existing cancers (Rossi, et al 2005). Another experiment showed that
the hydrophobic flavonoids of licorice root have abdominal fat lowering
and hypoglycemic effects. (Nakagawa, Kishida, Arai, Nishiyama, Mae,
2004). Glycyrrhiza glabra was
shown to have memory-strengthening activity in mice. In this same study
it reversed the amnesia that was induced by diazepam in mice (Parle,
Dhingra, & Kulkarni, 2004).
G. glabra has several known
adverse reactions to the glycerrhizic acid extract. Some side
effects noted were facial and dependent edema, headache, shortness of
breath, stiffness and upper abdominal pain (Schambelean, 1994).
These side effects are, however, resolved with lower doses.
The most serious side effect shown from ingestion of glycyrrhizic acid
is hyper-mineralcorticoidism which leads to hypertension. The
effect is believed to be entirely due to increased renal sodium
retention. Once ingested, the glycyrrhizic acid hydrolyzes in the
body to form glycyrrhetinic acid, which inhibits a steroid metabolizing
enzyme called 11 beta-HSD2 (Serra et al., 2001). The low levels
of this enzyme causes an increased access of cortisol to its receptors,
leading to renal sodium retention and loss of potassium (Serra et al.,
In a review of published reports on licorice, Stormer (1993) noted that
“for the most sensitive individuals, a regular daily intake of no more
than about 100 mg of glycyrrhizic acid seems to be enough to produce
adverse effects.” A dose of 10-12 mg/day was agreed to be a safe
dose even for those sensitive to the extract (Stormer, 1993).
Patients who are diagnosed with hypertension are cautioned by their
physicians to keep their blood pressure within acceptable limits.
Even in low doses, licorice root would be contraindicated for a patient
who is diagnosed with hypertension due to an underlying disease, such
as coronary artery disease, because of the effect glycyrrhizic acid on
the body (Sigurjonsdottir, 2001).
Brown, D. 1995. The Herb National
Society of America Encyclopedia of Herbs and Their Uses. Dorling
Kindersley Publishing Inc. New York. p135.
Foster, S. 2000. Licorice. Stephen Foster Group (http://www.stevenfoster.com/education/monograph/licorice.html)
Francischetti, I.M., R.Q. Monterio, & J.A. Guimaraes. 1997.
Identification of glycyrrhizin as a thrombin inhibitor.
Biochemistry Biophysiology Res Commun 237 (1):203.
Kowalchik, C. & W.H. Hylton. 1987. Rodale’s Illustrated
Encyclopedia of Herbs. Rodale Press. Pennsylvania. 360 –363pp
Nakagawa, K., H. Kishida, N. Arai, T. Nishiyama, & T. Mae. 2004.
Licorice flavonoids suppress abdominal fat accumulation and increase in
blood glucose level in obese diabetic KK-A(y) mice. Biol Pharm Bull. 27
Nam, C., S. Kim, Y. Sim, & I. Chang. 2003 Anti-acne effects of
Oriental herb extracts: a novel screening method to select anti-acne
agents. Skin Pharmacology Applied Skin Phsiology 16 (2):84-90
Parle, M., D. Dhingra, & S.K. Kulkarni. 2004 Memory-strengthing
activity of Glycyrrhiza glabra
in exteroceptive and interoceptive behavioral models. Med Food 7
Rossi, T., L. Benassi, C. Magnoni, A.I. Ruberto, A. Coppi, & G.
Baggio. 2005. Effects of glycyrrhizin on UVB-irradiated melanoma cells.
In Vivo 19 (1):319-22
Saeedi, M., K. Morteza-Semnani, M.R. Ghoreishi. 2003. The treatment of
atopic dermatitis with licorice gel. J Dermatolog Treat. 14 (3):153-157
Schambelan, M. 1994. Licorice ingestion and blood pressure
regulating hormones. Steroids 59 (2):127-130.
Serra, A, D.E. Uehlinger, P. Ferrari, B. Dick, B.M. Frey, F.J. Frey,
& B. Vogt. 2002. Glycyrrhetinic acid decreases plasma
potassium concentrations in patients with anuria. Journal of the
American Society of Nephrologists 13 (1):191-196.
Sigurjonsdottir, H.A. L. Franzon, K. Manhem, J. Ragnarsson, G.
Sigurdsson, and S. Wallerstedt. 2001.
Liquorice-induced rise in blood pressure: a linear dose-response
relationship. Journal of Human Hypertension 15 (8):549-552.
Stormer, F.C., R. Reidstat, & J. Alexander. 1993.
Glycyrrhizic acid in liquorice-evaluation of health hazard. Food
Chemistry and Toxicology 31 (4):303-312.
This paper was developed as part of the BIO 368 - Medical Botany
course offered at Wilkes University during the summer of 2005. Course
instructor was Kenneth M. Klemow, Ph.D.
The information contained herein is based on published sources, and
is made available for academic purposes only. No warrantees,
expressed or implied, are made about the medical usefulness or
dangers associated with the plant species in question.
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This page posted and maintained by Kenneth M.
Klemow, Ph.D., Biology Department,
Wilkes University, Wilkes-Barre,
PA 18766. (570) 408-4758,