Natural licorice, which has a very sweet taste, is extracted from the root of a shrub and used medicinally as a capsule, tablet, or liquid extract. Most licorice candy made in the US is flavored artificially and does not contain natural licorice. Glycyrrhizin is the active ingredient in natural licorice. For people who are particularly sensitive to the effects of glycyrrhizin, specially treated licorice products that contain a much lower amount of glycyrrhizin (about one tenth) are available. These products are called deglycyrrhizinated licorice.
People most often take licorice to suppress coughs, to soothe a sore throat, and to relieve stomach upset. Applied externally, it is said to soothe skin irritation (eg, eczema). There are not enough data to determine whether licorice is effective for stomach ulcers or complications caused by hepatitis C.
High doses of real licorice (> 1 oz/day) and glycyrrhizin cause renal Na and water retention, possibly leading to high BP, and K excretion, possibly causing low K levels. Increased K excretion can be a particular problem for people who have heart disease and for those who take digoxin or diuretics that also increase K excretion. Such people and those who have high BP should avoid taking licorice.
Licorice may increase the risk of premature delivery; thus, pregnant women should avoid licorice.
Last full review/revision May 2009 by Ara DerMarderosian, PhD
Content last modified October 2010