Licorice is a plant. You are probably most familiar with it as a flavoring in foods, beverages, and tobacco. The root is used to make medicine. Licorice is used for various digestive system complaints including stomach ulcers, heartburn, colic, and ongoing inflammation of the lining of the stomach (chronic gastritis).
Some people use licorice for sore throat, bronchitis, cough, and infections caused by bacteria or viruses. Licorice is also used for osteoarthritis, systemic lupus erythematosus (SLE), liver disorders, malaria, tuberculosis, food poisoning, and chronic fatigue syndrome (CFS).
Licorice is sometimes used along with the herbs Panax ginseng and Bupleurum falcatum to improve the function of the adrenal glands, especially in people who have taken steroid drugs long-term. Steroids tend to suppress the activity of the adrenal glands. The adrenal glands produce important hormones that regulate the body’s response to stress.
Licorice is also used in an herbal form called Shakuyaku-kanzo-to to increase fertility in women with a hormonal disorder called polycystic ovary syndrome. In combination with other herbs, licorice is also used to treat prostate cancer and the skin disorder known as eczema.
Some people use licorice as a shampoo to reduce oiliness in their hair.
Many “licorice” products manufactured in the U.S. actually don't contain any licorice. Instead, they contain anise oil, which has the characteristic smell and taste of “black licorice.”
Licorice interacts with many prescription medicines. Talk to your healthcare provider if you plan to start using licorice.
How effective is it?
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for LICORICE are as follows:
Possibly effective for...
- Heartburn (dyspepsia), when a combination of licorice and several other herbs is used. These other herbs are peppermint leaf, German chamomile, caraway, lemon balm, clown’s mustard plant, celandine, angelica, and milk thistle. The combination is packaged as a product called Iberogast or STW5. It was developed in 1961 in Germany. Research suggests that taking 1 mL orally three times daily over a period of 4 weeks significantly reduces severity of acid reflux and associated pain, cramping, nausea, and vomiting.
Insufficient evidence to rate effectiveness for...
- Muscle cramps. Preliminary clinical research suggests taking a specific combination of licorice and peony (Shakuyaku-kanzo-to) might reduce muscle cramps in people with liver disease (hepatic cirrhosis) or in people undergoing treatment for kidney failure (hemodialysis).
- Hepatitis. There is some evidence that some of the chemicals in licorice might be effective in treating hepatitis B and hepatitis C when given intravenously (by IV). But the studies involved too few patients to draw firm conclusions.
- Stomach ulcers. There is some evidence that specially prepared licorice will speed the healing of stomach ulcers.
- Weight loss. There is conflicting information about the use of licorice for weight loss. Licorice seems to reduce body fat. However, it causes water retention that can offset any change in body weight.
- Atopic dermatitis (eczema). There is conflicting evidence about the effectiveness of licorice for treating eczema.
- Chronic fatigue syndrome (CFS).
- Prostate cancer.
- Other conditions.
More evidence is needed to rate the effectiveness of licorice for these uses.
The chemicals contained in licorice are thought to decrease swelling, thin mucus secretions, decrease cough, and increase the chemicals in our body that heal ulcers.
Are there safety concerns?
Licorice is LIKELY SAFE for most people when consumed in amounts found in foods. It is POSSIBLY SAFE when consumed in larger amounts use as medicine, short-term. However, it is POSSIBLY UNSAFE when used in large amounts for more than four weeks. Consuming 30 grams or more of licorice daily for several weeks can cause severe side effects including high blood pressure, low potassium in the blood, weakness, paralysis, and occasionally brain damage in otherwise healthy people. In people who eat a lot of salt or have heart disease, kidney disease, or high blood pressure, as little as 5 grams per day can cause these problems.
Other side effects of licorice use include tiredness, absence of a menstrual period in women, headache, water and sodium retention, and decreased sexual interest and function in men.
People who chew tobacco flavored with licorice might develop high blood pressure and other serious side effects.
Special precautions & warnings:
Pregnancy and breast-feeding: It is UNSAFE to take licorice by mouth if you are pregnant. It might cause a miscarriage or early delivery. Not enough is known about the safety of licorice during breast-feeding. Don’t use licorice if you are pregnant or breast-feeding.
High blood pressure: Licorice can raise blood pressure. Don’t consume large amounts of it if you have high blood pressure.
Heart disease: Licorice can cause the body to store water, and this can make congestive heart failure worse. Licorice can also increase the risk of irregular heartbeat. Don’t consume licorice if you have heart disease.
Hormone-sensitive conditions such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Licorice might act like estrogen in the body. If you have any condition that might be made worse by exposure to estrogen, don’t use licorice.
A muscle condition caused by nerve problems (hypertonia): Licorice can cause the level of potassium to drop in the blood. This can make hypertonia worse. Avoid licorice if you have hypertonia.
Low potassium levels in the blood (hypokalemia): Licorice can lower potassium in the blood. If your potassium is already low, licorice might make it too low. Don’t use licorice if you have this condition.
Sexual problems in men: Licorice can lower a man’s interest in sex and also worsen erectile dysfunction (ED) by lowering levels of a hormone called testosterone.
Kidney disease: Overuse of licorice could make kidney disease worse. Don’t use it.
Surgery: Licorice might interfere with blood pressure control during and after surgery. Stop taking licorice at least 2 weeks before a scheduled surgery.
Are there interactions with medications?
Do not take this combination.
Warfarin (Coumadin) is used to slow blood clotting. The body breaks down warfarin (Coumadin) to get rid of it. Licorice might increase the breakdown and decrease the effectiveness of warfarin (Coumadin). Decreasing the effectiveness of warfarin (Coumadin) might increase the risk of clotting. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.
Be cautious with this combination.
Large amounts of licorice can decrease potassium levels in the body. Low potassium levels can increase the side effects of digoxin (Lanoxin).
Licorice seems to change hormone levels in the body. Taking licorice along with estrogen pills might decrease the effects of estrogen pills.
Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol, and others.
Ethacrynic acid (Edecrin)
Licorice can cause the body to get rid of potassium. Ethacrynic acid (Edecrin) can also cause the body to get rid of potassium. Taking licorice and ethacrynic acid (Edecrin) together might cause potassium to become too low.
Licorice can cause the body to get rid of potassium. Furosemide (Lasix) can also cause the body to get rid of potassium. Taking licorice and furosemide together might cause the potassium levels in your body to go too low.
Medications changed by the liver (Cytochrome P450 2B6 (CYP2B6) substrates)
Some medications are changed and broken down by the liver. Licorice might decrease how quickly the liver breaks down some medications. Taking licorice along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking licorice, talk to your healthcare provider if you take any medications that are changed by the liver.
Some of these medications changed by the liver include ketamine (Ketalar), phenobarbital, orphenadrine (Norflex), secobarbital (Seconal), dexamethasone (Decadron), and others.
Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)
Some medications are changed and broken down by the liver. Licorice might change how the liver breaks down some medications. Taking licorice along with medications that are broken down by the liver might increase or decrease the effects of these medications. Before taking licorice, talk to your healthcare provider if you are taking any medications that are changed by the liver.
Some medications changed by the liver include celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), and warfarin (Coumadin).
Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)
Some medications are changed and broken down by the liver. Licorice might change how the liver breaks down some medications. Taking licorice along with medications that are broken down by the liver might increase or decrease the effects of some medications. Before taking licorice, talk to your healthcare provider if you are taking any medications that are changed by the liver.
Some medications changed by the liver include lovastatin (Mevacor), ketoconazole (Nizoral), itraconazole (Sporanox), fexofenadine (Allegra), triazolam (Halcion), and many others.
Medications for high blood pressure (Antihypertensive drugs)
Large amounts of licorice seem to increase blood pressure. By increasing blood pressure, licorice might decrease the effectiveness of medications for high blood pressure.
Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), amlodipine (Norvasc), Hydrochlorothiazide (HydroDIURIL), furosemide (Lasix), and many others.
Medications for inflammation (Corticosteroids)
Some medications for inflammation can decrease potassium in the body. Licorice might also decrease potassium in the body. Taking licorice along with some medications for inflammation might decrease potassium in the body too much.
Some medications for inflammation include dexamethasone (Decadron), hydrocortisone (Cortef), methylprednisolone (Medrol), prednisone (Deltasone), and others.
Water pills (Diuretic drugs)
Large amounts of licorice can decrease potassium levels in the body. "Water pills" can also decrease potassium in the body. Taking licorice along with "water pills" might decrease potassium in the body too much.
Some "water pills" that can deplete potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, HydroDIURIL, Microzide), and others.
Are there interactions with herbs and supplements?
Herbs that affect the heart
Using too much licorice can decrease potassium in the body. This can damage the heart. Using licorice with herbs that can damage the heart might make this effect worse. Herbs that might damage the heart include digitalis, lily-of-the-valley, pheasant's eye, and squill.
Stimulant laxative herbs
Using too much licorice can decrease potassium in the body. Herbs that have a stimulant laxative effect can also lower potassium in the body. Using licorice along with these herbs can increase the risk of lowering potassium levels too much. Stimulant laxative herbs include aloe vera, alder buckthorn, European buckthorn, cascara sagrada, castor oil, rhubarb, and senna.
Drinking grapefruit juice when taking licorice might increase licorice's ability to cause potassium depletion.
Licorice use can increase sodium and water retention and increase blood pressure. Also, eating a lot of salt can make the side effects of licorice even worse.
What dose is used?
The following doses have been studied in scientific research:
- For upset stomach: A specific combination product containing licorice (Iberogast, Medical Futures, Inc) and several other herbs has been used in a dose of 1 mL three times daily.
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Source National Institute of Health