Natural licorice, which has a very sweet taste, is extracted from the root of a shrub (Glycyrrhiza glabra) and used medicinally as a capsule, tablet, or liquid extract. Most licorice candy made in the US is flavored artificially and does not contain natural licorice. Glycyrrhizin is the active ingredient in natural licorice. For people who are particularly sensitive to the effects of glycyrrhizin, specially treated licorice products that contain a much lower amount of glycyrrhizin (about one tenth) are available. These products are called deglycyrrhizinated licorice.
(See also Overview of Dietary Supplements Overview of Dietary Supplements Dietary supplements are the most commonly used of all integrative, complementary, and alternative therapies, primarily because they are widely available, relatively inexpensive, and can be bought... read more and National Institutes of Health (NIH): Licorice Root.)
Claims
People most often take licorice to suppress coughs, to soothe a sore throat, and to relieve stomach upset. Applied externally, it is said to soothe aphthous ulcers and skin irritation (eg, eczema) (1 References Natural licorice, which has a very sweet taste, is extracted from the root of a shrub (Glycyrrhiza glabra) and used medicinally as a capsule, tablet, or liquid extract. Most licorice... read more ). Licorice has also been claimed to help treat stomach ulcers and complications caused by hepatitis C or other liver diseases (2 References Natural licorice, which has a very sweet taste, is extracted from the root of a shrub (Glycyrrhiza glabra) and used medicinally as a capsule, tablet, or liquid extract. Most licorice... read more ).
Evidence
Evidence indicates that licorice in combination with other herbs provides relief from the symptoms of functional dyspepsia and irritable bowel syndrome (3 References Natural licorice, which has a very sweet taste, is extracted from the root of a shrub (Glycyrrhiza glabra) and used medicinally as a capsule, tablet, or liquid extract. Most licorice... read more ). However, clinical trials of both licorice alone and in combination are limited, and further evaluation is required. There are not enough data to determine whether licorice is effective for stomach ulcers or complications caused by hepatitis C.
A review and meta-analysis of 5 randomized controlled trials (609 subjects) reported that topical licorice prior to endotracheal intubation prevented postoperative sore throats by 56% and cough by 39% (4 References Natural licorice, which has a very sweet taste, is extracted from the root of a shrub (Glycyrrhiza glabra) and used medicinally as a capsule, tablet, or liquid extract. Most licorice... read more ). In a randomized controlled trial in 70 people with aphthous ulcers, licorice plus diphenhydramine solution was compared to diphenhydramine monotherapy. The main result was a faster healing time in patients treated with licorice plus diphenhydramine solution (5 References Natural licorice, which has a very sweet taste, is extracted from the root of a shrub (Glycyrrhiza glabra) and used medicinally as a capsule, tablet, or liquid extract. Most licorice... read more ).
Adverse Effects
At lower dosages or normal consumption levels, few adverse reactions are evident. However, high doses of real licorice (> 1 oz per day) and glycyrrhizin cause renal sodium and water retention, possibly leading to high blood pressure, and potassium excretion, possibly causing low potassium levels (pseudoaldosteronism). Increased potassium excretion can be a particular problem for people who have heart disease and for those who take digoxin or diuretics that also increase potassium excretion. Such people and those who have high blood pressure should avoid taking licorice.
Licorice may increase the risk of premature delivery; thus, pregnant women should avoid licorice.
Drug Interactions
Licorice may
Interact with warfarin and decrease its effectiveness, increasing the risk of blood clotting
Interact with digoxin by affecting potassium levels
Decrease effectiveness of antihypertensive drugs due to an increase in salt and water retention
Decrease effects of paclitaxel and cisplatin
Increase adverse effects of corticosteroids
Increase or decrease effects of estrogens
Also, some experts believe that licorice has some activity similar to a type of antidepressant called monoamine oxidase (MAO) inhibitors and thus may intensify adverse effects of these drugs.
(See table .)
References
1. Saeedi M, Morteza-Semnani K, Ghoreishi MR: The treatment of atopic dermatitis with licorice gel. J Dermatolog Treat 14(3):153-157, 2003. doi:10.1080/09546630310014369
2. Li X, Sun R, Liu R: Natural products in licorice for the therapy of liver diseases: progress and future opportunities. Pharmacol Res 144:210-226, 2019. doi: 10.1016/j.phrs.2019.04.025
3. Ottillinger B, Storr M, Malfertheiner P, et al: STW 5 (Iberogast®)—a safe and effective standard in the treatment of functional gastrointestinal disorders. Wien Med Wochenschr 163(3-4): 65-72, 2013. doi: 10.1007/s10354-012-0169-x
4. Kuriyama A, Maeda H: Topical application of licorice for prevention of postoperative sore throats in adults: a systematic review and meta-analysis. J Clin Anesth 54:25-32, 2019. doi: 10.1016/j.jclinane.2018.10.025
5. Akbari N, Asadimehr N, Kiani Z: The effects of licorice containing diphenhydramine solution on recurrent aphthous stomatitis: a double-blind, randomized clinical trial. Complement Ther Med 50:102401, 2020. doi:10.1016/j.ctim.2020.102401
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
National Institutes of Health (NIH), National Center for Complementary and Integrative Health: General information on the use of licorice root as a dietary supplement
Drugs Mentioned In This Article
| Drug Name | Select Trade |
|---|---|
diphenhydramine |
Aid to Sleep, Alka-Seltzer Plus Allergy, Aller-G-Time , Altaryl, Banophen , Benadryl, Benadryl Allergy, Benadryl Allergy Children's , Benadryl Allergy Dye Free, Benadryl Allergy Kapgel, Benadryl Allergy Quick Dissolve, Benadryl Allergy Ultratab, Benadryl Children's Allergy, Benadryl Children's Allergy Fastmelt, Benadryl Children's Perfect Measure, Benadryl Itch Stopping, Ben-Tann , Compoz Nighttime Sleep Aid, Diphedryl , DIPHEN, Diphen AF , Diphenhist, DiphenMax , Dytan, ElixSure Allergy, Genahist , Geri-Dryl, Hydramine, Itch Relief , M-Dryl, Nighttime Sleep Aid, Nytol, PediaCare Children's Allergy, PediaCare Nighttime Cough, PediaClear Children's Cough, PHARBEDRYL, Q-Dryl, Quenalin , Siladryl Allergy, Silphen , Simply Sleep , Sleep Tabs, Sleepinal, Sominex, Sominex Maximum Strength, Theraflu Multi-Symptom Strip, Triaminic Allergy Thin Strip, Triaminic Cough and Runny Nose Strip, Tusstat, Unisom, Uni-Tann, Valu-Dryl , Vanamine PD, Vicks Qlearquil Nighttime Allergy Relief, Vicks ZzzQuil Nightime Sleep-Aid |
digoxin |
Digitek , Lanoxicaps, Lanoxin, Lanoxin Pediatric |
warfarin |
Coumadin, Jantoven |
paclitaxel |
Onxol , Taxol |
cisplatin |
Platinol, Platinol -AQ |
