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 does it work?
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.
Possibly Effective for:
- Itchy and inflamed skin (eczema). There is some evidence that applying licorice to the skin can improve symptoms of eczema. Applying a gel containing licorice three times daily for 2 weeks seems to reduce redness, swelling, and itching.
- Heartburn (dyspepsia). Research suggests that taking a specific product containing licorice plus peppermint leaf, German chamomile, caraway, lemon balm, clown’s mustard plant, celandine, angelica, and milk thistle (Iberogast, Medical Futures, Inc) three times daily for 4 weeks can improve symptoms of heartburn.
- Bleeding. Early research suggests that applying a specific product containing alpinia, licorice, thyme, stinging nettle, and common grape vine to the skin reduces bleeding during surgery, but does not reduce time in surgery. Another early study suggests that applying the same product after dental surgery reduces bleeding.
- Canker sores. Research suggests that applying a patch containing licorice to the inside of the mouth for 16 hours daily for 8 days reduces the size of canker sores but does not speed up healing time. Other research suggests that applying licorice patches and gargling with warm water containing licorice reduces pain in patients with canker sores.
- Dental plaque. Early research suggests that using a toothpaste containing licorice twice dally does not reduce plaque, gingivitis, or bleeding when compared to toothpaste without licorice. Using mouthwash containing glycyrrhizin also does not seem to reduce plaque.
- Recurrent fevers (Familial Mediterranean fever). Early research suggests that taking a specific product containing andrographis, Siberian ginseng, schisandra, and licorice (ImmunoGuard, Inspired Nutritionals) reduces the duration, frequency, and severity of attacks of familial Mediterranean fever in children.
- Hepatitis. There is some evidence that certain components in licorice might be effective in treating hepatitis B and hepatitis C when given intravenously (by IV). However, the studies involved too few patients to draw firm conclusions.
- High cholesterol. Early research suggests that taking licorice root extract daily for 1 month reduces total cholesterol, low-density lipoprotein (LDL or “bad”) cholesterol, and triglyceride levels in people with high cholesterol.
- High potassium levels. Some research suggests that certain components in licorice decrease potassium levels in people with diabetes or kidney problems.
- Irritable bowel syndrome (IBS). Early research suggests that a product containing slippery elm bark, lactulose, oat bran, and licorice root can improve bowel movements in people with constipation-related to IBS. Stomach pain and bloating might also be reduced.
- Skin discoloration (melasma). Early research suggests that applying a cream containing licorice, emblica, and belides (Clariderm Clear) twice daily for 60 days is effective for lightening skin in people with skin discolorations.
- Muscle cramps. Early research suggests that taking a specific product containing 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).
- Abnormal levels of a hormone in the blood (neuroleptic-induced hyperprolactinemia). Early evidence suggests that taking 45 grams of a specific product containing peony and licorice (Peony-Glycyrrhiza Decoction, PGD) daily for 4 weeks reduces levels of a hormone called prolactin in women with high levels of prolactin, without affecting other hormone levels or mental symptoms. Other early research suggests that a product containing licorice and peony (shakutaku-kanzo-to) reduces prolactin levels in men in the short-term, but not in the long-term.
- Liver disease (nonalcoholic fatty liver disease). Early research suggests that taking 2 grams of licorice root extract daily for 2 months reduces test markers of liver injury in patients with liver disease not caused by drinking alcohol.
- Mouth sores (aral lichen planus). Early evidence suggests that administering a certain licorice component intravenously (by IV) improves symptoms of mouth sores in people with hepatitis C.
- Pain. Early research suggests that taking a combination of licorice root and peony root with Taiwanese tonic vegetable soup containing lily bulb, lotus seed, and jujube fruit reduces pain in cancer patients.
- Stomach ulcers. There is some evidence that specially prepared licorice will speed up the healing of stomach ulcers. However, other evidence suggests that similar licorice preparations do not improve stomach ulcer symptoms.
- Recovery after surgery. There is early evidence that gargling with a solution containing licorice for 30 seconds five minutes before receiving anesthesia and having a tube placed into the windpipe decreases cough and sore throat after surgery.
- Psoriasis. Early evidence suggests that applying a cream containing licorice and milk to the skin for 4 weeks does not reduce the amount of standard therapy needed, but does seem to improve skin peeling in patients with psoriasis.
- 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.
- Chronic fatigue syndrome (CFS).
- Prostate cancer.
- Other conditions.
Side Effects & Safety
Licorice is LIKELY SAFE for most people when consumed in amounts found in foods. Licorice is POSSIBLY SAFE when consumed in larger amounts for medicinal purposes and when applied to the skin for a short amount of time. However, it is POSSIBLY UNSAFE when used in large amounts for more than 4 weeks. Consuming licorice daily for several weeks or longer can cause severe side effects including high blood pressure, low potassium levels, 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. High consumption of licorice during pregnancy, about 250 grams of licorice per week, seems to increase the risk of early delivery. 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.
Major Interaction Do not take this combination
- Warfarin (Coumadin) interacts with LICORICE
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.
Moderate Interaction Be cautious with this combination
- Digoxin (Lanoxin) interacts with LICORICE
Large amounts of licorice can decrease potassium levels in the body. Low potassium levels can increase the side effects of digoxin (Lanoxin).
- Estrogens interacts with LICORICE
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) interacts with LICORICE
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.
- Furosemide (Lasix) interacts with LICORICE
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) interacts with LICORICE
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) interacts with LICORICE
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) interacts with LICORICE
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) interacts with LICORICE
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) interacts with LICORICE
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) interacts with LICORICE
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.
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.