Herb: Licorice Root

Licorice-Root-FieldandHerbsLicorice Root

Most licorice root grows in Greece, Turkey, and Asia.  Licorice is harvested from the plants’ roots and underground stems. Licorice supplements are available as capsules, tablets, and liquid extracts. Centuries ago, licorice root was used in Greece, China, and Egypt for stomach inflammation and upper respiratory problems. Anise oil is often used instead of licorice root to flavor licorice candy. Licorice root also has been used as a sweetener. Today, people use licorice root as a dietary supplement for digestive problems, menopausal symptoms, cough, and bacterial and viral infections. People also use it as a shampoo.

How It Works in the Body

The two major constituents of licorice 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. Licorice may also have antiviral properties. Licorice flavonoids, as well as the closely related chalcones, help heal digestive tract cells. They are also potent antioxidants 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.

An extract of licorice, called liquiritin, has been used as a treatment for melasma, a pigmentation disorder of the skin. In a preliminary trial, 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 licorice (DGL) tablets were just as effective at healing and maintaining the healing of stomach ulcers. Chewable DGL may also be helpful in treating ulcers of the duodenum, the first part of the small intestine. Capsules of DGL may not work for ulcers, however, as DGL must mix with saliva to be activated. One preliminary human trial has found DGL used as a mouthwash was effective in quickening the healing of canker sores.

Studied Benefits

  • Peptic Ulcer: Licorice root has a long history of use for soothing inflamed and injured mucous membranes in the digestive tract. Flavonoids in licorice may also inhibit growth of H. pylori.
  • Canker Sores: Deglycyrrhizinated licorice (DGL) and warm water applied to the inside of the mouth may speed the healing of canker sores. Chewable DGL tablets may have the same effect.
  • Colic: A soothing tea made from chamomile, vervain, licorice, fennel, and lemon balm has been shown to relieve colic more effectively than placebo.
  • Common Cold: Throat Coat tea, which contains licorice root, can ease the symptoms of the common cold.
  • Sore Throat: In one study, Throat Coat tea was effective in providing rapid, temporary relief of sore throat pain in people with acute pharyngitis.
  • Epilepsy: The Chinese herb bupleurum is included in two herbal formulas, sho-saiko-to and saiko-keishi-to. Both have been shown to be helpful for epilepsy.
  • Gastroesophageal Reflux Disease: Chewing deglycyrrhizinated licorice may help mucous membranes heal.
  • Hepatitis: One of the active constituents in licorice, glycyrrhizin, has been used to some benefit in Japan as an injected therapy for hepatitis B and C.
  • HIV: Licorice inhibits HIV reproduction in test tubes, supplementing with it may be safe and effective for long-term treatment of HIV infection.
  • Liver Cirrhosis: The Chinese herb bupleurum is a component of the formula sho-saiko-to, which was shown in one preliminary trial to liver cancer risk in people with liver cirrhosis.
  • Asthma: Licorice, which has a soothing effect on bronchioles, has traditionally been used for asthma.
  • Chronic Fatigue Syndrome: A case report described a man with CFS whose symptoms improved after taking 2.5 grams of licorice root daily.
  • Cold Sores: Licorice in the form of a cream or gel may be applied directly to cold sores in order to speed healing and reduce pain.
  • Cough: Licorice has a long history of use for relieving coughs.
  • Crohn’s Disease: Licorice is an anti-inflammatory herb historically recommended by doctors for people with Crohn’s disease
  • Eczema: Licorice may help eczema through its anti-inflammatory effects and its ability to affect the immune system.
  • Gastritis: Licorice root has been traditionally used to soothe stomach inflammation and injury. Its flavonoid constituents have been found to stall the growth of H. pylori in test tube studies.
  • Genital Herpes: Licorice root contains antiviral substances, and ointments containing related substances are effective in treating herpes infections.
  • Hay Fever: The Japanese herbal formula known as sho-seiryu-to has been shown to reduce symptoms, such as sneezing, for people with hay fever.
  • Indigestion: Licorice protects the mucous membranes lining the digestive tract by increasing the production of mucin, a compound that protects against the adverse effects of stomach acid and various harmful substances.
  • Heartburn: (see indigestion)
  • Menopause: Licorice is an herb with weak estrogen-like actions similar to soy. In one trial, a formula containing licorice, burdock, dong quai, wild yam, and motherwort reduced menopause symptoms.
  • Shingles: Licorice has been used as a topical treatment for shingles and postherpetic neuralgia.
  • Ulcerative Colitis: Licorice is an anti-inflammatory and soothing herb that may be effective in the treatment of ulcerative colitis.

Traditional Uses

Licorice 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 flavoring. It has also been used in Traditional Chinese Medicine to treat conditions ranging from diabetes to tuberculosis.

Precautions to Consider

In large amounts and with long-term use, licorice root can cause high blood pressure and low potassium levels, which could lead to heart and muscle problems. Some side effects are thought to be due to a chemical called glycyrrhizic acid. Licorice that has had this chemical removed (called DGL for deglycyrrhizinated licorice) may not have the same degree of side effects.

Taking licorice root containing glycyrrhizinic acid with medications that reduce potassium levels such as diuretics might be bad for your heart.

Pregnant women should avoid using licorice root as a supplement or consuming large amounts of it as food.

Resources to Dive Into

Amer M, Metwalli M. Topical liquiritin improves melasma. Int J Dermatol 2000;39:299-301.

Armanini D, Bonanni G, Palermo M. Reduction of serum testosterone in men by licorice. New Engl J Med1999;341:1158 [letter].

Bardhan KD, Cumberland DC, Dixon RA, Holdsworth CD. Clinical trial of deglycyrrhizinised liquorice in gastric ulcer. Gut 1978;19:779-82.

Beil W, Birkholz C, Sewing KF. Effects of flavonoids on parietal cell acid secretion, gastric mucosal prostaglandin production and Helicobacter pylori growth. Arzneimittelforschung 1995;45:697-700.

Blumenthal M, Busse WR, Goldberg A, et al, eds. The Complete Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative Medicine Communications, 1998, 161-2.

Das SK, Gulati AK, Singh VP. Deglycyrrhizinated licorice in aphthous ulcers. J Assoc Physicians India1989; 37:647.

Josephs RA, Guinn JS, Harper ML, Askari F. Liquorice consumption and salivary testosterone concentrations. Lancet 2001;358:1613-4.

Kassir ZA. Endoscopic controlled trial of four drug regimens in the treatment of chronic duodenal ulceration. Ir Med J 1985;78:153-6.

Morgan AG, McAdam WAF, Pacsoo C, Darnborough A. Comparison between cimetidine and Caved-S in the treatment of gastric ulceration, and subsequent maintenance therapy. Gut 1982;23:545-51.

Murray MT. The Healing Power of Herbs. Rocklin, CA: Prima Publishing, 1995, 228-39.

Soma R, Ikeda M, Morise T, et al. Effect of glycyrrhizin on cortisol metabolism in humans. Endocrin Regulations 1994;28:31-4.

Whorwood CB, Shepard MC, Stewart PM. Licorice inhibits 11ß-hydroxysteroid dehydrogenase messenger ribonucleic acid levels and potentiates glucocorticoid hormone action. Endocrinology 1993;132:2287-92.

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