Licorice | Health Notes at WWSM | Health Information at WWSM

Liquorice

Also indexed as: DGL (Licorice)

Botanical names: Glycyrrhiza glabra, Glycyrrhiza uralensis

Parts used and where grown

Originally from central Europe, liquorice now grows all across Europe and Asia. The root is used medicinally.

Liquorice has been used in connection with the following conditions (refer to the individual health concern for complete information):

Science Ratings	Health Concerns
	Infection Peptic ulcer (chewable DGL)
	Colic (in combination with vervain, fennel and lemon balm) Epilepsy (in combination with bupleurum, peony root, pinellia root, cassia bark, ginger root, jujube fruit, Asian ginseng root, and Asian scullcap root) Gastro-oesophageal reflux disease (GERD) (DGL) Hepatitis (intravenous glycyrrhizin) HIV support Infections (viral) Mouth ulcers (DGL)
	Asthma Chronic fatigue syndrome Cold sores (topical) Cough Crohn’s disease Eczema Gastritis Genital herpes (topical) Hay fever (Sho-seiryu-to: contains liquorice, cassia bark, schisandra, ma huang [ephedra], ginger, peony root, pinellia, and asiasarum root) Hepatitis (oral glycyrrhizin) Indigestion and heartburn (DGL) Melasma (topical liquirtin) Menopause Shingles (herpes zoster)/postherpetic neuralgia (topical gel) Ulcerative colitis
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Historical or traditional use (may or may not be supported by scientific studies)

Liquorice has a long and highly varied record of uses. It was and remains one of the most important herbs in Traditional Chinese Medicine. Among its most consistent and important uses are as a demulcent (soothing, coating agent) in the digestive and urinary tracts, to help with coughs, to soothe sore throats, and as a flavouring. It has also been used in Traditional Chinese Medicine to treat conditions ranging from diabetes to tuberculosis.

Active constituents

The two major constituents of liquorice are glycyrrhizin and flavonoids. According to test tube studies, glycyrrhizin has anti-inflammatory actions and may inhibit the breakdown of the cortisol produced by the body.¹ ² Liquorice may also have antiviral properties, although this has not been proven in human pharmacological studies. Liquorice flavonoids, as well as the closely related chalcones, help heal digestive tract cells. They are also potent anti-oxidants and work to protect liver cells. In test tubes, the flavonoids have been shown to kill Helicobacter pylori, the bacteria that causes most ulcers and stomach inflammation.³ However, it is unclear whether this action applies to the use of oral liquorice for the treatment of ulcers in humans.

An extract of liquorice, called liquiritin, has been used as a treatment for melasma, a pigmentation disorder of the skin. In a preliminary trial,⁴ topical application of liquiritin cream twice daily for four weeks led to a 70% improvement, compared to only 20% improvement in the placebo group.

A preliminary trial found that while the acid-blocking drug cimetidine (Tagamet®) led to quicker symptom relief, chewable deglycyrrhizinated liquorice (DGL) tablets were just as effective at healing and maintaining the healing of stomach ulcers.⁵ Chewable DGL may also be helpful in treating ulcers of the duodenum, the first part of the small intestine.⁶ Capsules of DGL may not work for ulcers, however, as DGL must mix with saliva to be activated.⁷ One preliminary human trial has found DGL used as a mouthwash was effective in quickening the healing of mouth ulcers.⁸

How much is usually taken?

There are two types of liquorice, “standard” liquorice and “de-glycyrrhizinated” liquorice (DGL). Each type is suitable for different conditions. The standard liquorice containing glycyrrhizin should be used for respiratory infections, chronic fatigue syndrome or herpes (topical). Liquorice root in capsules, 5–6 grams per day, can be used. Concentrated extracts, 250–500 mg three times per day, are another option. Alternatively, a tea can be made by boiling 1/2 ounce (14 grams) of root in 1 pint (500 ml) of water for fifteen minutes, then drinking two to three cups (500–750 ml) per day. Long-term internal use (more than two to three weeks) of high amounts (over 10 grams per day) of glycyrrhizin-containing products should be attempted only under the supervision of a doctor. Liquorice creams or gels can be applied directly to herpes sores three to four times per day.

DGL is prepared without the glycyrrhizin in order to circumvent potential safety problems (see below), and is used for conditions of the digestive tract, such as ulcers. For best results, one 200–300 mg tablet is chewed three times per day before meals and before bed.⁹ For mouth ulcers, 200 mg of DGL powder can be mixed with 200 ml warm water, swished in the mouth for three minutes, and then expelled. This may be repeated three or four times per day.

Are there any side effects or interactions?

Liquorice products that include glycyrrhizin may increase blood pressure and cause water retention.¹⁰ Some people are more sensitive to this effect than others. Long-term intake (more than two to three weeks) of products containing more than 1 gram of glycyrrhizin (the amount in approximately 10 grams of root) daily is the usual amount required to cause these effects. Consumption of 7 grams liquorice (containing 500 mg glycyrrhizin) per day for seven days has been shown to decrease serum testosterone levels in healthy men by blocking the enzymes needed to synthesise testosterone.¹¹ However, in another study, a similar amount of liquorice had only a small and statistically insignificant effect on testosterone levels.¹² As a result of these possible side effects, long-term intake of high levels of glycyrrhizin is discouraged and should only be undertaken if prescribed by a qualified healthcare professional. Consumption of plenty of fresh fruits and vegetables to increase potassium intake is recommended to help decrease the chance of side effects. According to the German Commission E monograph, liquorice is inadvisable for pregnant women as well as for people with liver and kidney disorders.¹³

De-glycyrrhizinated liquorice extracts do not cause these side effects since they contain no glycyrrhizin.

Are there any drug interactions?
Certain medicines may interact with liquorice. Refer to drug interactions for a list of those medicines.

References
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.