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Licorice (Glycyrrhiza glabra), Deglycyrrhizinated Licorice, Carbenoxolone Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain licorice. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with a pharmacist or health care professional before starting.
This monograph discusses licorice; deglycyrrhizinated licorice (DGL), which does not contain glycyrrhizinic acid, a chemical in licorice that causes many side effects; and carbenoxolone, a chemical that can be processed out of licorice. Scientists have studied these three substances for the following health problems: Peptic ulcer disease | Licorice extracts, DGL and carbenoxolone have been studied for treating peptic ulcers. DGL (but not carbenoxolone) may offer some benefits. However, these studies have been small, with flaws in their designs, and results of different studies have disagreed with each other. Therefore, it is unclear whether there is any benefit from licorice for this condition. | Apthous ulcers, canker sores | Some research suggests that licorice extracts, DGL and carbenoxolone may provide benefits for treating cankers sores. However, studies have been small, with flaws in their designs. The safety of DGL makes it an attractive therapy if it does speed healing of these sores, but it is not clear at this time whether there is truly any benefit. | Bleeding stomach ulcers caused by aspirin | Although there has been some study of DGL in this area, it is not clear what effects DGL has on gastrointestinal bleeding. | Herpes simplex virus | Laboratory studies have found that DGL may hinder the spread and infection of herpes simplex virus. Studies in humans have been small, but they suggest that topical application of carbenoxolone cream may improve healing and prevent recurrence. | Viral hepatitis | The licorice extracts DGL and carbenoxolone have been proposed as possible therapies for viral hepatitis. Animal studies have investigated the mechanism of licorice in hepatitis, and studies in humans have shown some benefits with a patented intravenous licorice preparation that is not available in the United States. Studies using oral licorice have been small, with flaws in their designs. Therefore, it is not clear whether there is any benefit from oral licorice for hepatitis treatment. | High potassium levels resulting from abnormally low aldosterone levels | In theory, because of the known effects of licorice on the kidney, there may be some benefits of licorice for high potassium levels caused by a condition called hypoaldosteronism. There is early evidence in humans in support of this use. However, a qualified health care professional should supervise treatment. | Familial Mediterranean fever | A small clinical pilot study and laboratory study results of a multi-ingredient preparation containing licorice, called Immunoguard, suggest efficacy in managing familial Mediterraneann fever. Well-designed study of licorice alone is necessary to make a recommendation. | Genital herpes | Available studies have not found any benefit from carbenoxolone cream when applied topically to treat genital herpes infections. | Atopic dermatitis | Topical licorice extract gel has been shown to be effective in the treatment of atopic dermatitis in preliminary study in humans. Further research is needed to confirm these results. | Reducing body fat mass | Preliminary data show that licorice may reduce body fat mass. Further research is needed to confirm these results. |
Licorice has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult a health care professional before taking licorice for any unproven use. Adrenal insufficiency (Addison's disease)
Allergy
Antibacterial
Antimicrobial
Antioxidant
Antispasmodic
Antitumor
Aplastic anemia
Asthma
Bacterial infections
Bad breath
Body fat reducer
Breast cancer
Bronchitis
Cancer
Chronic fatigue syndrome
Colitis
Colorectal cancer
Constipation
Coronavirus
Cough
Cysts
Dental hygiene
Depression
Detoxification
Diabetes
Diverticulitis
Dysmenorrhea (painful menstruation)
Eczema
Epstein-Barr virus
Fever
Functional dyspepsia | Gastroesophageal reflux disease
Gentamicin-induced kidney damage
Graft healing
High cholesterol
HIV
Hormone regulation
Hot flashes
Hyperpigmentation disorders
Immune system stimulation
Inflammation
Inflammatory skin disorders
Laryngitis
Liver protection
Lung cancer
Melasma
Menopausal symptoms
Methicillin-resistance Staphylococcus aureus
Muscle cramps
Obesity
Osteoarthritis
Plaque
Polycystic ovarian syndrome
Prostate cancer
Pruritus
Respiratory syncytial virus
Rheumatoid arthritis
SARS
Skin disorders
Sore throat
Stomach upset
Tobacco-associated lung cancer
Urinary tract inflammation |
Allergies People should avoid licorice if they have a known allergy to licorice, any component of licorice or any member of the Fabaceae (Leguminosae) plant family. Signs of allergy may include rash, itching or shortness of breath. Side Effects Licorice contains a chemical called glycyrrhizic acid, which causes many side effects. DGL has had the glycyrrhizic acid removed and is considered safer for use. Many of the adverse effects of licorice result from the actions it has on hormone systems in the body. By altering the activities of certain hormones, licorice may cause electrolyte disturbances in some people. These disturbances can include sodium and fluid retention, low potassium levels, metabolic alkalosis and seizures. Licorice has caused high blood pressure and negative effects on the brain (hypertensive encephalopathy), with symptoms of serious headache, nausea, vomiting and one-sided weakness. Electrolyte abnormalities may also lead to irregular heartbeats, heart attack, kidney damage, muscle weakness or muscle breakdown. People with congestive heart failure, coronary heart disease, kidney or liver disease, fluid retention, high blood pressure and hormonal abnormalities and those taking diuretics should avoid taking licorice. Abnormally low testosterone levels in men or high prolactin or estrogen levels in women have also been reported. These adverse effects may make it difficult to become pregnant and may cause menstrual abnormalities. Reduced body fat mass has been observed. Acute pseudo-aldosteronism syndrome has been associated with licorice. Paralysis has been reported in a patient taking licorice that contributed to low potassium levels. Thyrotoxic periodic paralysis has been associated with licorice. Ocular side effects such as central retinal vein occlusion have been associated with licorice. High doses of licorice may cause temporary vision problems or loss. A case report exists of licorice-induced low potassium levels associated with dropped head syndrome. Pregnancy And Breast-Feeding Licorice cannot be recommended during pregnancy and breast-feeding because of the risk of abnormalities caused by altered hormone levels and the possibility of premature labor.
Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with a health care professional or pharmacist before using herbs or dietary supplements. Interactions With Drugs In general, prescription drugs should be taken one hour before licorice or two hours after licorice because licorice may increase the absorption of many drugs. Increased absorption may increase the activities and side effects of some drugs including nitrofurantoin. Because the toxicity of digoxin (Lanoxin) is increased when potassium levels are low, people who take digoxin and are interested in using licorice should discuss this with their health care professional. Increased monitoring may be necessary. Licorice may reduce the effects of blood pressure or diuretic (urine-producing) drugs, including hydrochlorothiazide and spironolactone. Furthermore, use of licorice with hydrochlorothiazide may cause potassium levels to fall too low and lead to dangerous complications. Other drugs that can also cause potassium levels to fall too low and are best avoided when using licorice include insulin, sodium polystyrene (kayexalate) and laxatives. Licorice may increase the adverse effects associated with corticosteroids, such as prednisolone, and monoamine oxidase inhibitors, such as phenelzine (Nardil). Licorice may reduce the effects of birth control pills, hormone replacement therapies and testosterone therapy. Drugs that may increase the tendency for irregular heart rhythms, such as erythromycin or amiodarone (Cordarone), are best avoided when using licorice. In theory, licorice may increase the risk of bleeding when used with anticoagulants (blood thinners) or antiplatelet drugs. Examples include warfarin (Coumadin), heparin and clopidogrel (Plavix). Some pain relievers may also increase the risk of bleeding if used with licorice. Examples include aspirin, ibuprofen (Motrin, Advil) and naproxen (Naprosyn, Aleve, Anaprox). Chewing tobacco may increase the toxicity of licorice gums by causing electrolyte disturbances. Licorice was shown to increase absorption of diclofenac gel in a rat study. Phosphate salts have been shown to increase licorice absorption. Liver metabolism of certain drugs may be affected by licorice. Agents acting on serotonin may also interact with licorice. Interactions With Herbs And Dietary Supplements Low potassium levels may occur if licorice is used with herbs that have laxative properties, such as senna or psyllium. Herbs that increase the risk of bleeding, such as Ginkgo biloba and garlic ( Allium sativum); those that have diuretic properties, such as horsetail ( Equisetum arvense); and supplements that lower blood pressure, such as hawthorn ( Crataegus laevigata), may have a greater tendency for adverse effects when used with licorice. Licorice may also increase adverse effects associated with herbs that have possible monoamine oxidase inhibitor activity, such as St. John's wort ( Hypericum perforatum). Agents acting on serotonin may also interact with licorice. Licorice may affect the way the liver breaks down certain herbs and supplements. Interactions With Laboratory Values Licorice has been shown to decrease cortisol, ACTH (adrenocorticotrophic hormone), aldosterone and potassium levels in animals. Increases in renin and sodium levels have also been observed.
The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with a health care professional before starting therapy; always read the recommendations on a product’s label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas. The expert panel German Commission E recommends that licorice be used for only four to six weeks unless under direct medical supervision. However, this is based on the use of relatively large daily doses (five to 15 grams per day). Many experts believe that extended treatments may be safe if lower doses are used. In a four-week study in healthy individuals, recommended doses were well tolerated, with few adverse effects. There are no standard or well-studied doses of licorice, and many different doses are used traditionally. Adults (Aged 18 Or Older) Licorice powdered root (4 percent to 9 percent glycyrrhizin): Doses of one to four grams taken by mouth daily, divided into three or four doses, have been used. Licorice fluid extract (10 percent to 20 percent glycyrrhizin): Doses of two to four milliliters per day have been taken by mouth. A dose of 3.5 grams a day of a commercial preparation of licorice has been studied for body fat mass reduction. DGL extract tablets: Doses of 380 to 1140 milligrams three times daily taken by mouth 20 minutes before meals have been used. Carbenoxolone gel or cream: A 2 percent cream or gel has been applied five times a day for seven to 14 days for herpes simplex virus skin lesions. Children (Younger Than 18) There are not enough scientific data to recommend licorice for use in children, and licorice is not recommended because of potential side effects.
Licorice and licorice extracts have been suggested as treatments for many conditions. However, there is not enough scientific evidence to support the use of licorice or licorice extract for any medical condition. Licorice may increase the risk of electrolyte disturbances and hormonal abnormalities and should be avoided in those with heart disease, high blood pressure or underlying hormonal disorders. It should also be avoided in pregnant or breast-feeding women and in children. It is possible that licorice may increase the risk of bleeding. Safety of use beyond four weeks has not been extensively studied. Consult a health care professional immediately if you have any side effects. The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.
- Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
- National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research
Selected Scientific Studies: Licorice Natural Standard reviewed more than 370 articles to prepare the professional monograph from which this version was created. Some of the more recent studies are listed below: - Amaryan G, Astvatsatryan V, Gabrielyan E, et al. Double-blind, placebo-controlled, randomized, pilot clinical trial of ImmunoGuard: a standardized fixed combination of Andrographis paniculata Nees, with Eleutherococcus senticosus Maxim, Schizandra chinensis Bail and Glycyrrhiza glabra L. extracts in patients with familial Mediterranean fever. Phytomedicine 2003;May, 10(4):271-285.
- Arase Y, Ikeda K, Murashima N, et al. The long term efficacy of glycyrrhizin in chronic hepatitis C patients. Cancer 1997;79(8):1494-1500.
- Armanini D, Bonanni G, Mattarello MJ, et al. Licorice consumption and serum testosterone in healthy man. Exp Clin Endocrinol Diabetes 2003;Sep, 111(6):341-343.
- Armanini D, De Palo CB, Mattarello MJ, et al. Effect of licorice on the reduction of body fat mass in healthy subjects. J Endocrinol Invest 2003;Jul, 26(7):646-650.
- Belhadj-Tahar H, Nassar B, Coulais Y, et al. Acute pseudo-aldosteronism syndrome induced by liquorice. Therapie 2003;Jul-Aug, 58(4):375-378.
- Carbonell-Barrachina AA, Aracil P, Garcia E, et al. Source of arsenic in licorice confectionery products. J Agric Food Chem 2003;Mar 12, 51(6):1749-1752.
- Cheng CJ, Chen YH, Chau T, Lin SH. A hidden cause of hypokalemic paralysis in a patient with prostate cancer. Support Care Cancer 2004;Nov, 12(11):810-812.
- Cinatl J, Morgenstern B, Bauer G, et al. Glycyrrhizin, an active component of liquorice roots, and replication of SARS-associated coronavirus. Lancet 2003;Jun 14, 361(9374):2045-2046.
- Elinav E, Chajek-Shaul T. Licorice consumption causing severe hypokalemic paralysis. Mayo Clin Proc 2003;Jun, 78(6):767-768.
- Eriksson JW, Carlberg B, Hillorn V. Life-threatening ventricular tachycardia due to liquorice-induced hypokalaemia. J Intern Med 1999;245(3):307-310.
- Fujioka T, Kondou T, Fukuhara A, et al. Efficacy of a glycyrrhizin suppository for the treatment of chronic hepatitis C: a pilot study. Hepatol Res 2003;May, 26(1):10-14.
- Harada T, Ohtaki E, Misu K, et al. Congestive heart failure caused by digitalis toxicity in an elderly man taking a licorice-containing chinese herbal laxative. Cardiology 2002;98(4):218.
- Hinoshita F, Ogura Y, Suzuki Y, et al. Effect of orally administered shao-yao-gan-cao-tang (Shakuyaku-kanzo-to) on muscle cramps in maintenance hemodialysis patients: a preliminary study. Am J Chin Med 2003;31(3):445-453.
- Hughes J, Sellick S, King R, Robbe IJ. Re: "Preterm birth and licorice consumption during pregnancy." Am J Epidemiol 2003;Jul 15, 158(2):190-191; author reply, 191.
- Kamei J, Nakamura R, Ichiki H, Kubo M. Antitussive principles of Glycyrrhizae radix, a main component of the Kampo preparations Bakumondo-to (Mai-men-dong-tang). Eur J Pharmacol 2003;May 23, 469(1-3):159-163.
- Kang DG, Sohn EJ, Mun YJ, et al. Glycyrrhizin ameliorates renal function defects in the early-phase of ischemia-induced acute renal failure. Phytother Res 2003;Sep, 17(8):947-951.
- Liu J, Manheimer E, Tsutani K, Gluud C. Medicinal herbs for hepatitis C virus infection: a Cochrane hepatobiliary systematic review of randomized trials. Am J Gastroenterol 2003;Mar, 98(3):538-544.
- Nokhodchi A, Nazemiyeh H, Ghafourian T, et al. The effect of glycyrrhizin on the release rate and skin penetration of diclofenac sodium from topical formulations. Farmaco 2002;Nov, 57(11):883-888.
- Russo S, Mastropasqua M, Mosetti MA, et al. Low doses of liquorice can induce hypertension encephalopathy. Am J Nephrol 2000;20(2):145-148.
- Saeedi M, Morteza-Semnani K, Ghoreishi MR. The treatment of atopic dermatitis with licorice gel. J Dermatolog Treat 2003;Sep, 14(3):153-157.
- Serra A, Uehlinger DE, Ferrari P, et al. Glycyrrhetinic Acid decreases plasma potassium concentrations in patients with anuria. J Am Soc Nephrol 2002;13(1):191-196.
- Strandberg TE, Andersson S, Jarvenpaa AL. Risk factors for preterm delivery. Lancet 2003;Feb 1, 361(9355):436; author reply, 436-437.
- van Rossum TG, Vulto AG, Hop WC, et al. Glycyrrhizin-induced reduction of ALT in European patients with chronic hepatitis C. Am J Gastroenterol 2001;96(8):2432-2437.
Last updated June 30, 2005
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