A member of the pea family, licorice root has been used since ancient times both as food and as medicine. In Chinese herbology, licorice is an ingredient in nearly all herbal formulas for the traditional purpose of "harmonizing" the separate herbs involved.

The herb licorice contains a substance called glycyrrhizin. When taken in high enough amounts, glycyrrhizin produces effects similar to those of the natural hormone aldosterone, causing fluid retention, increased blood pressure, and loss of potassium.1-4 To prevent this, manufacturers have found a way to remove glycyrrhizin from licorice, producing the safer product deglycyrrhizinated licorice (DGL).

DGL has shown some promise for the treatment of ulcers.7Weak evidence hints that it might also help prevent ulcers caused by anti-inflammatory drugs.8

Licorice, in the form of a dissolving patch, is also sometimes recommended for relieving the discomfort of canker soresand other mouth sores.29,30

Creams containing whole licorice (often combined with chamomile extract) are advocated for a variety of skin diseases, including eczema, psoriasis, and herpes, but as yet there is only supporting evidence for the first of these uses. (See What is the Scientific Evidence for Licorice ?).

Whole licorice, not DGL, is used as an expectorant for respiratory problems such as coughs and asthma.

Licorice has been suggested as a treatment for chronic fatigue syndrome (CFS), based on the observation that people with CFS appear to suffer from low levels of certain adrenal hormones. The glycyrrhizin portion of licorice may relieve symptoms by mimicking the effects of these hormones. However, this is a fairly dangerous approach to treatment that should be tried only under medical supervision. In addition, studies of drugs that even more closely imitate adrenal hormones have not found benefit.

Licorice extracts are used intravenously in Japan for treatment of viral hepatitis.27,28 However, there is no definite evidence that this treatment is effective; even if this were established, it would not imply that oral licorice would have a similar effect; furthermore, the high dosages used for treatment of chronic hepatitis may cause an elevation of blood pressure and other serious medical problems. Warning: Do not inject preparations of licorice designed for oral use.