Licorice (Glycyrrhiza glabra) has been used in food and as medicine for thousands of years. Also known as "sweet root," licorice root contains a compound that is about 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. It acts as a demulcent, a soothing, coating agent, and as an expectorant, meaning it helps get rid of phlegm. It is still used today for several conditions, although not all its uses are supported by scientific evidence.

Licorice that has the active ingredient of glycyrrhiza can have serious side effects. Another type of licorice, called DGL or deglycyrrhizinated licorice, doesn't seem to have the same side effects and is sometimes used to treat peptic ulcers, canker sores, and reflux (GERD). Whole licorice is still sometimes suggested for cough, asthma, and other breathing problems. Topical preparations are used for eczema and other skin problems.

Licorice grows wild in some parts of Europe and Asia. A perennial that grows 3 - 7 feet high, licorice has an extensive branching root system. The roots are straight pieces of wrinkled, fibrous wood, which are long and cylindrical (round) and grow horizontally underground. Licorice roots are brown on the outside and yellow on the inside. Licorice supplements are made from the roots and underground stems of the plant.

Licorice root is often used for a variety of conditions.

Peptic ulcers

Deglycyrrhizinated licorice (DGL) is often suggested as a treatment for stomach ulcers, although there's only mixed evidence about whether it works. A few studies have found that DGL and antacids helped treat ulcers as well as some prescription drugs. However, since antacids were combined with DGL, it's not possible to know how much of the benefit came from DGL alone.

One animal study found that aspirin coated with licorice reduced the number of ulcers in rats by 50%. (High doses of aspirin often cause ulcers in rats.) In one study, licorice root fluid extract was used to treat 100 patients with stomach ulcers -- 86 of whom had not improved with conventional medication -- for 6 weeks. Ulcers disappeared in 22 people; 90% of participants got better. Other studies have found that DGL had no effect on peptic ulcers in humans.

Canker sores (Apthous ulcers)

One small study found that people with canker sores who gargled 4 times per day with DGL dissolved in warm water found pain relief.

Eczema

In one study, licorice gel, applied to the skin, helped relieve symptoms of itching, swelling, and redness. A gel with 2% licorice worked better than a gel with 1% licorice.

Dyspepsia (indigestion, GERD)

Some preliminary studies suggest that a specific herbal formula containing licorice, called Iberogast or STW 5, may help relieve symptoms of indigestion or GERD. This herbal formula also contains peppermint and chamomile, two herbs often used for indigestion.

Upper respiratory infections (cold, cough)

Licorice is a traditional treatment for cough and asthma. Studies have shown mixed results as to whether it works.

Weight loss

One study found that a preparation of licorice may reduce body fat. Fifteen people of normal weight consumed 3.5 g of licorice each day for 2 months. Body fat was measured before and after treatment. Licorice appeared to reduce body fat mass and to suppress the hormone aldosterone; however, the people in the study retained more water.

Another study found that a topical preparation of glycyrrhetinic acid (a component of licorice) reduced the thickness of fat on the thigh in human subjects. A third study found that people who took 900 mg of licorice flavonoid oil daily for 8 weeks had decreases in body fat, body weight, body mass index, and LDL cholesterol levels. More studies are needed to say if licorice really helps reduce fat. In addition, taking licorice long term has a number of health risks.

People who regularly take large amounts of licorice -- more than 20 g/day -- may raise blood levels of the hormone aldosterone, which can cause serious side effects, including headache, high blood pressure, and heart problems. For people who already have high blood pressure or heart or kidney disease, as little as 5 g/day can cause these side effects. Further studies are needed.

Licorice products are made from peeled and unpeeled dried root. There are powdered and finely cut root preparations made for teas, tablets, and capsules, as well as liquid extracts. Some licorice extracts do not contain glycyrrhizin. These extracts are known as deglycyrrhizinated licorice (DGL), and do not seem to have the undesired side effects of other forms of licorice. Some studies suggest DGL may be better for stomach or duodenal ulcers. DGL may offer protection against ulcer formation when taken with aspirin.

Pediatric

Older children who have a sore throat can chew a piece of licorice root or drink licorice tea. Ask your doctor to help you determine the right dose for your child. Don't give a child licorice tea for more than a day without talking to your doctor. Never give any licorice tea to an infant or toddler.

Adult

Licorice can be taken in the following forms:

• Dried root: 1 - 5 g as an infusion or decoction (boiled), 3 times daily
• Licorice 1:5 tincture: 2 - 5 mL, 3 times daily
• Standardized extract: 250 - 500 mg, 3 times daily, standardized to contain 20% glycyrrhizinic acid
• DGL extract: 0.4 - 1.6 g, 3 times daily, for peptic ulcer
• DGL extract 4:1: chew 300 - 400 mg, 3 times daily 20 minutes before meals, for peptic ulcer

Don't use these doses of licorice for longer than a week without talking to your doctor due to the risk of potentially dangerous side effects.

The use of herbs is a time honored approach to strengthening the body and treating disease. Herbs, however, contain components that can trigger side effects and that can interact with other herbs, supplements, or medications. For these reasons, you should take herbs with care, preferably under the supervision of a health care provider in the field of botanical medicine.

Licorice with glycyrrhizin may cause serious side effects. Too much glycyrrhizin causes a condition called pseudoaldosteronism, which can cause a person 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.

Although the most dangerous effects mostly happen with high doses of licorice or glycyrrhizin, smaller amounts of licorice may cause side effects. Some people have muscle pain or numbness in the arms and legs. To be safe, ask your health care provider to monitor your use of licorice.

People with the following conditions should not take licorice:

• Heart failure
• Heart disease
• Hormone-sensitive cancers, such as breast, ovarian, uterine, or prostate cancer
• Fluid retention
• High blood pressure (hypertension)
• Diabetes
• Kidney disease
• Liver disease
• Low potassium (hypokalemia)
• Erecetile dysfunction

Pregnant or breastfeeding women should not take licorice.

Don't use any licorice product for longer than 4 - 6 weeks.

Licorice may interfere with several medications, including the ones listed below. If you are taking any medication, ask your doctor before taking licorice.

• ACE inhibitors and diuretics -- If you are taking angiotensin converting enzyme (ACE) inhibitors or diuretics for high blood pressure, you should not use licorice products. Licorice could cause these medications to not work as well or could make side effects worse, including a build-up of potassium in the body. ACE inhibitors include:
  • Captopril (Capoten)
  • Benazepril (Lotensin)
  • Enalapril (Vasotec)
  • Lisinopril (Prinivil, Zestril)
  • Gosinopril (Monopril)
  • Ramipril (Altace)
  • Perindopril (Aceon)
  • Quinapril (Accupril)
  • Moexipril (Univasc)
  • Trandolapril (Mavik)
• Digoxin -- Because licorice may dangerously increase the risk of toxic effects from digoxin, do not take this herb with this medication.
• Corticosteroids -- Licorice may increase the effects of corticosteroid medications. Talk to your doctor before using licorice with any corticosteroids.
• Insulin or drugs for diabetes -- Licorice may have an effect on blood sugar levels.
• Laxatives -- Licorice may cause potassium loss in people taking stimulant laxatives.
• MAO inhibitors -- Licorice may make the effects of this class of antidepressant stronger.
• Oral contraceptives -- There have been reports of women developing high blood pressure and low potassium levels when they took licorice while on oral contraceptives.
• Warfarin (Coumadin) -- Licorice may decrease the levels of this blood-thinner in the body, meaning it may not work as well.
• Medications processed by the liver -- Licorice may interfere with several medications processed by the liver, including celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), phenytoin (Dilantin), piroxicam (Feldene), phenobarbital, and secobarbital (Seconal).

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