Licorice is traditionally used for coughs and as a soothing remedy for the skin. People also take it for inflammation, bronchitis, arthritis, constipation, and skin conditions such as acne. Health care providers, such as naturopaths, may prescribe licorice root products for peptic ulcer, chronic gastritis, and to treat primary adrenocortical insufficiency. Licorice root extracts are active against bacterial infections such as staph and strep and may have antiviral properties. Licorice root may also destroy the yeast that causes Candida infections. Despite the many medical effects described, licorice also has potential side effects; please see sections entitled "Precautions" and "Possible Interactions."

Spanish licorice (Glycyrrhiza glabra) grows wild in some parts of Europe and Asia. A perennial that grows 3 to 7 feet high, licorice has an extensive branching root system. The roots are straight pieces of wrinkled, fibrous wood, which are long and cylindrical and grow horizontally underground. Licorice roots are brown on the outside and yellow on the inside. Glycyrrhizin, an active ingredient in licorice root, is 50 times sweeter than sugar.

Licorice products are made from the roots and underground stems of the plant. Glycyrrhizin and glycyrrhetic acid are the most important substances in licorice. The roots also contain coumarins, flavonoids, volatile oils, and plant sterols. Licorice must always be used with caution because glycyrrhizin and glycyrrhetic acid can harm the adrenal glands.

Licorice products are made from peeled and unpeeled dried root. There are powdered and finely cut root preparations, as well as dried and liquid extracts. Some licorice root extracts have had the harmful compounds removed. These extracts are known as deglycyrrhizinated licorice (DGL), and do not seem to harm the adrenal glands or have the undesired side effects of other forms of licorice. DGL may be better for gastric or duodenal ulcers. Scientific studies show that DGL reduces inflammation and is as effective as some prescription drugs for gastric ulcers. In fact, DGL may offer protection against ulcer formation when taken with aspirin. In addition, it may enhance the effectiveness of antiulcer medications such as cimetidine.

Pediatric

For sore throat treatment in older children, a piece of licorice root may be chewed or licorice tea may be used. The appropriate dose of tea for a child should be determined by adjusting the recommended adult dose to account for the child's weight. Most herbal dosages for adults are calculated on the basis of a 150 lb (70 kg) adult. Therefore, if the child weighs 50 lb (20-25 kg), the appropriate dose of licorice for this child would be 1/3 of the adult dosage.

Adult

Licorice can be taken in the following forms:

• Dried root: 1 to 5 g as an infusion or decoction three times per day
• Licorice tincture: 2 to 5 mL three times per day
• DGL extract: 0.4 to 1.6 g three times per day for peptic ulcer
• DGL extract 4:1: in chewable tablet form 300 to 400 mg 20 minutes before meals for peptic ulcer

You should be very careful if you are taking large amounts of licorice products or if you chew licorice-flavored tobacco or use other licorice-flavored products. If so, you are at risk for licorice side effects and toxicities.

If you take more than 20 g of licorice a day, you might have a bad reaction. Too much glycyrrhizin causes a condition called pseudoaldosteronism, which makes you overly sensitive to a hormone in the adrenal cortex. This condition can lead to headaches and fatigue. It may also cause water retention, which can lead to leg swelling and other problems. An overdose of glycyrrhizin can lead to harmful conditions such as high blood pressure and even heart attack. These symptoms can show up within one week if you're taking more than 100 g of glycyrrhizin every day.

Although the most dangerous effects generally only occur with high doses of licorice or glycyrrhizin, side effects may occur even with average amounts of licorice. Some people experience muscle pain and/or numbness in the arms and legs. Too much licorice can also cause weight gain. These problems can probably be avoided if dosages are kept within the recommended guidelines. It is safest, though, to have use of licorice monitored by your health care provider.

Licorice should not be used in the case of high blood pressure, or a kidney, heart, or liver condition. Licorice should also not be used during pregnancy or while nursing. Finally, use of any licorice product is not recommended for longer than four to six weeks.

If you are taking angiotensin-converting enzyme (ACE) inhibitors or diuretics (except potassium-sparing diuretics) to regulate blood pressure, do not use licorice products. Licorice could interfere with the effectiveness of these medications or could worsen possible side effects.

Because licorice may dangerously increase the risk of toxic effects from digoxin, this herb should not be taken with this medication.

Licorice may increase the effects of corticosteroid medications. You should consult with your doctor before using licorice with any corticosteroids.

There have been reports of women developing high blood pressure and low potassium levels when they took licorice while on oral contraceptives. Therefore, you should avoid licorice if you are taking birth control medications.

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