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 of 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, does not seem to have the same side effects and is sometimes used to treat peptic ulcers, canker sores, and reflux (GERD). Practitioners still sometimes suggest whole licorice 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 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 (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.
DGL is often suggested as a treatment for stomach ulcers, although it is not clear 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 is 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 people 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.
One small study suggested that gargling with DGL dissolved in warm water 4 times per day helped reduce pain among people with canker sores.
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.
Preliminary studies suggest that a specific herbal formula containing licorice, called Iberogast or STW 5, may help relieve symptoms of indigestion or gastroesophageal reflux disease (GERD). This herbal formula also contains peppermint and chamomile, two herbs often used for indigestion.
Licorice is a traditional treatment for cough, asthma, and sore throat. One study found that gargling with licorice before getting anesthesia cut the incidence of postoperative sore throat by half.
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 experienced reductions 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.
Preliminary research suggests licorice may be effective at reducing hot flashes. One study found that licoricee seems more effective than HRT in improving hot flash duration.
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. More research is 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.
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. DO NOT give a child licorice tea for more than a day without talking to your doctor. Never give licorice tea to an infant or toddler.
Your health care provider should determine the dose of licorice that's right for you. DO NOT use licorice for longer than a week without talking to your doctor due to the risk of potentially dangerous side effects.
Pregnant or breastfeeding women should not take licorice. Some studies suggest that taking licorice during pregnancy can increase the risk of stillbirth.
DO NOT use any licorice product for longer than 4 to 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:
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).
Diuretics, hormonal medications, and many other medications interact with licorice.
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