Licorice Overview

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 2 3} To prevent this, manufacturers have found a way to remove glycyrrhizin from licorice, producing the safer product deglycyrrhizinated licorice (DGL).

Eczema

Creams containing whole licorice (often combined with extract of chamomile) are in wide use as "natural hydrocortisone creams." However, there is only preliminary supporting evidence for this use. In one double-blind, placebo-controlled trial of 30 people, licorice gel at 2% was more effective than placebo or 1% gel for reducing symptoms of eczema . ⁴ Licorice has constituents that increase the activity of naturally occurring (or artificially supplied) corticosteroids, ⁵ and this might explain some of the benefits seen. In addition, licorice contains licochalcone A, a substance hypothesized to have anti-inflammatory effects. ⁶

Ulcer Treatment

Two controlled studies suggest that regular use of DGL in a combination product also containing antacids can heal ulcers as effectively as drugs in the Zantac family. ⁷ Unfortunately, these studies do not prove that DGL was effective; antacids themselves can help heal ulcers, and in any case the studies were not double-blind . (For information on why this matters, see Why Does This Database Rely on Double-blind Studies? )

Furthermore, if it does work, DGL would have to be taken continuously to avoid ulcer recurrence. In some cases, drug treatment can prevent the recurrence of ulcers permanently by eradicating the bacteria Helicobacter pylori. There is no evidence as yet that DGL can do the same.

Ulcer Prevention

A very preliminary study suggests that DGL might help prevent ulcers caused by aspirin and related medications (such as ibuprofen). ⁸

For supportive treatment of ulcer pain along with conventional medical care, the standard dose is two to four 380-mg tablets of DGL taken before meals and at bedtime. The same tablets can be allowed to slowly dissolve in the mouth for possible relief of mouth sore pain.

A typical dose of whole licorice is 5 to 15 g daily. However, we do not recommend the use of doses this high for more than a few weeks. For long-term consumption, about 0.3 g of licorice root daily should be safe for most adults. (See Safety Issues.) Individuals who wish to take a higher dose should do so only under the supervision of a physician.

For the treatment of eczema, psoriasis, or herpes, 2% licorice gel or cream is applied twice daily to the affected area.

1. Stewart PM, Wallace AM, Valentino R, Burt D, Shackleton CH, Edwards CR. Mineralocorticoid activity of liquorice: 11-beta-hydroxysteroid dehydrogenase deficiency comes of age. Lancet. 2(8563):821-4.
2. Conn JW, Rovner DR, Cohen EL. Licorice-induced pseudoaldosteronism. Hypertension, hypokalemia, aldosteronopenia, and suppressed plasma renin activity. JAMA. 205(7):492-6.
3. Epstein MT, Espiner EA, Donald RA, Hughes H. Effect of eating liquorice on the renin-angiotensin aldosterone axis in normal subjects. Br Med J. 1(6059):488-90.
4. Saeedi M, Morteza-Semnani K, Ghoreishi MR. The treatment of atopic dermatitis with licorice gel. J DermatologTreat. 2003 Sep;14:153-157.
5. Teelucksingh S, Mackie AD, Burt D, McIntyre MA, Brett L, Edwards CR. Potentiation of hydrocortisone activity in skin by glycyrrhetinic acid. Lancet. 335(8697):1060-3.
6. Kolbe L, Immeyer J, Batzer J, Wensorra U, tom Dieck K, Mundt C, Wolber R, Stäb F, Schönrock U, Ceilley RI, Wenck H. Anti-inflammatory efficacy of Licochalcone A: correlation of clinical potency and in vitro effects. Arch Dermatol Res. 298(1):23-30.
7. Morgan AG, Pacsoo C, McAdam WA. Maintenance therapy: a two year comparison between Caved-S and cimetidine treatment in the prevention of symptomatic gastric ulcer recurrence. Gut. 26(6):599-602.
8. Rees WD, Rhodes J, Wright JE, Stamford LF, Bennett A. Effect of deglycyrrhizinated liquorice on gastric mucosal damage by aspirin. Scand J Gastroenterol. 14(5):605-7.