Licorice (Glycyrrhiza glabra) is a flavorful herb that has been used in food and medicinal remedies for thousands of years. Also known as "sweet root," licorice root contains a compound that is roughly 50 times sweeter than sugar. Licorice root has been used in both Eastern and Western medicine to treat a variety of illnesses ranging from the common cold to liver disease. This herb has long been valued as a demulcent (soothing, coating agent) and continues to be used by professional herbalists today to relieve respiratory ailments (such as allergies, bronchitis, colds, sore throats, and tuberculosis), stomach problems (including, possibly, heartburn from reflux or some other cause and gastritis), inflammatory disorders, skin diseases, and liver problems.

Licorice root is often used to prevent and treat stomach ulcers. In fact, healthcare practitioners in Europe and Japan often prescribe a synthetic form of licorice for stomach ulcers. Although this drug is not available in the United States, many herbalists prescribe combination herbal remedies containing licorice for people with this painful health condition.

Animal studies and early trials in humans support the value of licorice for stomach ulcers. One animal study recently found that aspirin coated with licorice reduced the number of ulcers in rats by 50 percent. (High doses of aspirin often cause ulcers in rats). Earlier studies in humans have found that preparations containing glycyrrhizin (an active compound in licorice) may be as effective as leading anti-ulcer medications in relieving pain associated with stomach ulcers and preventing the ulcers from recurring. In one study, licorice root fluid extract was used to treat 100 patients with stomach ulcers (of which 86 had not improved from conventional medication) for 6 weeks. Ninety percent of patients improved; ulcers totally disappeared in 22 of these patients.

Active compounds in licorice root are also used to help prevent and treat chronic hepatitis (liver inflammation). In one study of Japanese patients with hepatitis C, those who received intravenous treatment with glycyrrhizin, cysteine, and glycine for an average of 10 years were significantly less likely to develop liver cancer and cirrhosis (progressive liver failure) than those who received placebo. In a second study of 57 patients with hepatitis C, glycyrrhizin (in doses ranging from 80 to 240 mg/day) significantly improved liver function after only one month. These effects diminished after glycyrrhizin treatment was discontinued, however.

Emerging studies are beginning to suggest that licorice may also play a role in the treatment of heart disease. In one recent study, people with high cholesterol experienced a significant reduction in total cholesterol, LDL ("bad") cholesterol, and trigylceride levels after taking licorice root extracts for one month. The extract also reduced systolic blood pressure by 10 percent. These measures returned to their previous, elevated levels when the participants stopped taking the licorice supplements. Earlier studies in mice produced similar results. Licorice root extract reduced the risk of atherosclerosis in these animals.

Preliminary studies also suggest that licorice may play a role in the treatment of human immunodeficiency virus (HIV) and Japanese encephalitis. One early study of only 3 people with HIV suggested that intravenous glycyrrhizin may prevent replication of HIV, but larger studies have yet to duplicate these findings. A laboratory study found that glycyrrhizin inhibited the growth of Japanese encephalitis virus in test tubes, but further studies in humans are needed to confirm these preliminary findings. Experimental studies also suggest that active compounds in licorice may have estrogen-like effects. It is not clear at this time whether such effects are helpful or harmful to people with breast cancer.

Despite these promising findings, there is ongoing debate in the scientific community regarding the value and side effects of licorice products. People who regularly consume large amounts of licorice (more than 20 g/day) may inadvertently raise blood levels of the hormone aldosterone, which can cause serious side effects including headache, high blood pressure, and heart problems. Further studies are needed.

Licorice 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. Licorice products are made from the roots and underground stems of the plant.

Glycyrrhizin, one of the main active ingredients in licorice, is believed to contribute to the herb's many healing properties. Laboratory studies have shown that glycyrrhizin reduces inflammation, promotes secretion of mucous (usually through coughing), soothes irritation, and stimulates the activity of the adrenal glands. The roots also contain coumarins, flavonoids, volatile oils, and plant sterols.

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 do not contain the compounds that stimulate the adrenal glands. 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 stomach 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 1:5 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

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, contain active substances that can trigger side effects and that can interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, preferably under the supervision of a practitioner knowledgeable in the field of botanical medicine.

High doses of licorice (more than 20 g/day) may cause serious side effects. Too much glycyrrhizin causes a condition called pseudoaldosteronism, which can cause an individual to become overly sensitive to a hormone in the adrenal cortex. This condition can lead to headaches, fatigue, high blood pressure, and even heart attacks. 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.

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.

People with high blood pressure, obesity, diabetes, or kidney, heart, or liver conditions should avoid licorice. This herb should also not be used by pregnant or breastfeeding women or by men with decreased libido or other sexual dysfunctions. Use of any licorice product is not recommended for longer than four to six weeks.

If you are currently being treated with any of the following medications, you should not use licorice without first talking to your healthcare provider:

Ace-inhibitors and diuretics
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.

Aspirin
Animal studies suggest that licorice may reduce stomach irritation as well as the risk of stomach ulcers associated with aspirin.

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

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

Insulin
Licorice may enhance some of the adverse effects of insulin.

Laxatives
Licorice may cause substantial potassium loss in people taking stimulant laxatives.

Oral contraceptives
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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