Licorice (Glycyrrhiza glabra)

Licorice: Medical Uses

Licorice has been used for peptic ulcer disease, canker sores, and cough. It is used topically for eczema, psoriasis, and herpes.

Historical Uses

Historically, licorice has been used as a flavoring agent in candy, tobacco, and soft drinks. Licorice syrup was used as a cough remedy. For years, licorice root has been valued in Germany and China and in Ayurvedic medicine.


Licorice comes from a small shrub that grows in temperate climates.

Part Used

• Root

Major Chemical Compounds

  • • Glycyrrhizin
  • • Flavonoids
  • • Phenolic compounds
  • • Glicophenone
  • • Glicoisoflavone
  • • Phytosterols
  • • Coumarins ()

Licorice: Clinical Uses

Licorice has been used for peptic ulcer disease, canker sores, cough, and chronic fatigue syndrome (under supervision). It is used topically for eczema, psoriasis, and herpes. It is also used for its antibacterial activity and its antiparasitic, antitumor, and estrogenic activity. It may be used for anti-HIV effects.

Mechanism of Action

Licorice does not inhibit the release of gastric acid, but rather stimulates normal defense mechanisms by improving blood supply, increasing the amount and quality of substances that line the intestinal tract, and increasing the life span of cells in the intestinal tract. It possesses mineralocorticoid properties that can lead to retention of sodium and water, potassium loss, and high blood pressure. It has phytoestrogenic effects. It also has antibacterial effects on methicillin-resistant and methicillin-sensitive strains of Staphylococcus aureus. It has anti-HIV action from triterpene glycyrrhizin (extracted from the root of Glycyrrhiza radix) that may interfere with virus-cell binding. Glycyrrhizin has anti-inflammatory properties, blocks C5, inhibits the lytic pathway, and may prevent tissue injury.

Licorice: Dosage

Deglycyrrhizinated licorice (DGL) is the safest form of licorice because the chemical compound glycyrrhizin has been removed. Glycyrrhizin is structurally similar to cortisol, which causes adverse effects.

Tablets: Six to eight 250-mg chewable tablets daily.

Capsules: 400 to 500 mg up to 6 times daily.

Powdered root: 1 gram up to three times daily.

For peptic ulcers: Take DGL tablets, not capsules, between meals. Do not exceed dosage and do not take for more than 4 to 6 weeks.

Side Effects

Whole licorice root may raise blood glucose levels. If patient takes more than 3 grams per day for more than 6 weeks, monitoring of blood pressure and electrolytes is suggested, along with increasing potassium intake. Foods high in potassium include figs, bananas, raisins, avocado, and baked potato with skin.

Other side effects include hypertension, sodium and water retention (aldosterone-like effects), hypokalemia, vision loss, and decreased libido in men. Licorice acts as an adrenal stimulant in the whole plant; use DGL, the safest form of licorice (see Dosage). Licorice root in large amounts can cause Cushing’s syndrome, hypokalemia, and increased toxicity of cardiac glycosides.


  • • Diabetes
  • • Hypertension
  • • Liver and kidney disease
  • • Hypokalemia ()

Herb-Drug Interaction

Whole licorice root should not be administered with spironolactone (WHO, 1999) or amiloride. It may increase potassium loss when given with thiazide diuretics and laxatives, and it may interfere with or intensify the effects of digitalis glycosides.

Pregnancy and Breast-Feeding

Licorice is not recommended during pregnancy. No restrictions are known for breast-feeding.

Summary of Studies

Farese et al. (1991). Licorice-induced hypermineralocorticoidism, noted after ingesting licorice root (more than 3 g/day for more than 6 weeks) or glycyrrhizin (100 mg/day) may cause sodium and water retention, hypertension, hypokalemia, and suppression of the renin-aldosterone system through a pseudo-aldosterone action of glycyrrhetinic acid. Monitoring of blood pressure, electrolytes was suggested, along with increasing potassium intake.

Licorice: Warnings

  • • Use whole licorice root only under a health-care practitioner’s care.
  • • Whole licorice root may raise blood sugar levels, increase blood pressure, and cause other severe side effects.
  • • Don’t take licorice root if you have diabetes, high blood pressure, liver disease, kidney disease, or low potassium.
  • • Don’t use licorice root if you take spironolactone, amiloride, thiazide diuretics (medications that promote the flow of urine), laxatives, or heart medications.
  • • Licorice root isn’t recommended during pregnancy or breast-feeding. Consult your health-care practitioner.