The medicinally used part of licorice is the root and dried rhizome of the low-growing shrub Glycyrrhiza glabra. Currently, most licorice is produced in Greece, Turkey, and Asia.
Licorice has been used in ancient Greece, China, and Egypt, primarily for gastritis (inflammation of the stomach) and ailments of the upper respiratory tract. Ancient Egyptians prepared a licorice drink for ritual use to honor spirits of the pharaohs. Its use became widespread in Europe and Asia for numerous indications.
In addition to its medicinal uses, licorice has been used as a flavoring agent, valued for sweetness (glycyrrhizin, a component of licorice, is 50 times sweeter than table sugar). The generic name "glycyrrhiza" stems from ancient Greek, meaning "sweet root." It was originally used as flavoring for licorice candies, although most licorice candy is now flavored with anise oil. Licorice is still used in sub-therapeutic doses as a sweetening agent in herbal medicines, lozenges, and tobacco products (doses low enough that significant adverse effects are unlikely).
Licorice has a long history of medicinal use in Europe and Asia. At high doses, there are potentially severe side effects, including hypertension (high blood pressure), hypokalemia (low blood potassium levels) and fluid retention. Most adverse effects have been attributed to the chemical component glycyrrhiza (or glycyrrhizic acid). Licorice can be processed to remove the glycyrrhiza, resulting in DGL (deglycyrrhizinated licorice), which does not appear to share the metabolic disadvantages of licorice.
Bois doux (French), Fabaceae (family), gan cao, glabrene, glabridin, glucoliquiritin, glycyrrhetenic acid, glycyrrhiza, Glycyrrhiza glabra, Glycyrrhiza uralensis Fisher, glycyrrhizin, isoflavan, isoliquiritigenin, kanzo (Japanese), LA, Lakrids (Danish), Lakritzenwurzel (German), leguminose, licochalcone-A, licorice root, Liquiritiae radix, Liquiritia officinalis, liquirizia (Italian), liquorice, prenyllicoflavone, radix glycyrrhizae, réglisse (French), shao-yao-gan-cao-tang (Shakuyanu-kanzo-tou), STW 5-11 (extracts from bitter candy tuft, matricaria flower, peppermint leaves, caraway, licorice root and lemon balm), Suβholzwurzel, sweet root, sweet wood, yashimadhu (Sanskrit).
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Apthous ulcers / canker sores
Some research suggests that licorice extracts, DGL and the drug carbenoxolone may provide benefits for treating cankers sores. However, studies have been small, with flaws in their designs. The safety of DGL makes it an attractive therapy if it does speed healing of these sores, but it is not clear at this time whether there is truly any benefit.
Topical licorice extract gel has been shown to be effective in the treatment of atopic dermatitis in preliminary human study. Further research is needed to confirm these results.
Bleeding stomach ulcers caused by aspirin
Although there has been some study of DGL in this area, it is not clear what effects DGL has on gastrointestinal bleeding.
Familial Mediterranean Fever (FMF)
Early study of a multi-ingredient preparation containing licorice, called Immunoguard, suggests possible effects in managing FMF. Well-designed study of licorice alone is necessary before a recommendation can be made.
Herpes simplex virus
Laboratory studies have found that DGL may hinder the spread and infection of herpes simplex virus. Studies in humans have been small, but they suggest that topical application of carbenoxolone cream may improve healing and prevent recurrence.
High potassium levels resulting from abnormally low aldosterone levels
In theory, because of the known effects of licorice, there may be some benefits of licorice for high potassium levels caused by a condition called hypoaldosteronism. There is early evidence in humans in support of this use. However, research is preliminary and a qualified health care provider should supervise treatment.
Peptic ulcer disease
Licorice extracts, DGL and carbenoxolone have been studied for treating peptic ulcers. DGL (but not carbenoxolone) may offer some benefits. However, most studies are poorly designed and some results conflict. Therefore, it is unclear whether there is any benefit from licorice for this condition.
Reducing body fat mass
Preliminary data shows that licorice may reduce body fat mass. Further research is needed to confirm these results.
The licorice extracts DGL and carbenoxolone have been proposed as possible therapies for viral hepatitis. Further research is needed before a recommendation can be made.
Available studies have not found any benefit from carbenoxolone cream when applied topically to the skin to treat genital herpes infections.