Licorice (Glycyrrhiza glabra)

Table of Contents

1. Five Thousand Years of Medicinal Use
2. Active Compounds
3. Peptic Ulcers and Gastritis (DGL)
4. Adrenal Support and Cortisol Modulation
5. Cough and Respiratory Conditions
6. Antiviral Activity and Liver Support
7. Skin and Inflammatory Conditions
8. Forms and Preparations
9. Doses Used and Official Limits
10. Cautions and Contraindications
11. Featured Videos

Five Thousand Years of Medicinal Use

Licorice (the root of Glycyrrhiza glabra and related species) is one of the oldest and most widely travelled medicinal plants in the world — its very name comes from the Greek for “sweet root.” From the physicians of ancient Egypt, Greece, and Rome to its central place in Chinese medicine and its later fame in the sweet-shops of England, the same sweet root was prized across cultures for soothing the cough and throat, calming the stomach, and serving as a gentle restorative — the fuller story is told in the dedicated History & Traditional Use article.

Back to Table of Contents

Active Compounds

• Glycyrrhizin (glycyrrhizic acid) — the principal active compound; responsible for the sweetness, the cortisol-prolonging effect, the antiviral activity, and the potential side effects
• Glycyrrhetinic acid — the metabolite of glycyrrhizin; the active form responsible for inhibition of 11-beta-HSD2 (the enzyme that converts cortisol to inactive cortisone)
• Flavonoids — including liquiritin, liquiritigenin, and isoliquiritigenin, with antioxidant, anti-inflammatory, and gastroprotective activity
• Isoflavonoids — including glabridin and glabrene, with weak phytoestrogenic and antimicrobial activity
• Triterpenoid saponins — including soyasaponins, with mild expectorant and adrenal-supporting activity

Back to Table of Contents

Peptic Ulcers and Gastritis (DGL)

Deglycyrrhizinated licorice (DGL) is widely used by herbal practitioners for peptic ulcer disease, gastritis, and functional dyspepsia. By removing glycyrrhizin (and with it the cortisol-related side effect profile), DGL retains the gastric-protective properties of the flavonoid fraction without the potential for hypertension or fluid retention.

Proposed mechanisms of DGL's GI-protective action include:

• Stimulation of mucin production from gastric epithelial cells, thickening the protective mucus layer
• Promotion of cell turnover in the gastric and duodenal lining
• Anti-inflammatory effects on the gastric epithelium
• Direct inhibitory activity against Helicobacter pylori (the bacterium implicated in most peptic ulcers)
• Soothing of esophageal and gastric irritation in reflux

Practitioners favour the chewable form (380-760 mg, chewed before meals), reasoning that chewing stimulates mucus production; in that practice, capsule forms are regarded as less effective for ulcer protection, though still used for symptomatic gastritis.

Back to Table of Contents

Adrenal Support and Cortisol Modulation

Glycyrrhizin (and its metabolite glycyrrhetinic acid) inhibits the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (11-beta-HSD2), which normally converts active cortisol into inactive cortisone in target tissues. Inhibiting this enzyme effectively prolongs the action of endogenous cortisol throughout the body.

This mechanism produces a recognizable clinical pattern — both the desired effect and the dose-limiting toxicity:

• Therapeutic application — integrative practitioners use low-dose licorice in patients with documented hypocortisolism, late-stage hypothalamic-pituitary-adrenal-axis depletion, or treatment-resistant fatigue with low salivary cortisol, reasoning that it extends the activity of the body's own (low) cortisol output, supporting energy and stress tolerance
• Dose-limiting toxicity — at higher doses or prolonged use, the same mechanism produces apparent mineralocorticoid excess: sodium retention, potassium loss, fluid retention, and hypertension. This is called pseudohyperaldosteronism

Integrative protocols that use glycyrrhizin-containing licorice for adrenal support describe small doses (75-150 mg of glycyrrhizin per day) for limited periods (typically 4-12 weeks), with blood pressure and electrolytes monitored. The official reference points: the European Commission's Scientific Committee on Food set 100 mg of glycyrrhizin a day (the amount in about 60 g of licorice sweets) as an upper limit for regular intake that protects most people, adding that it may not protect people with high blood pressure or with electrolyte or water-balance disorders; the WHO/FAO Joint Expert Committee on Food Additives (JECFA) judged 100 mg a day unlikely to cause adverse effects in most adults; and the European Medicines Agency (EMA) licorice root monograph (Revision 1, 2026) sets 4 weeks as the maximum for its digestive use. The EMA reports overdose cases with use beyond 4 weeks or high intakes, with water retention, low blood potassium (hypokalaemia), high blood pressure, heart-rhythm disorders and hypertensive encephalopathy (brain dysfunction caused by very high blood pressure) — the last two are medical emergencies.

Back to Table of Contents

Cough and Respiratory Conditions

Licorice has classical use as a demulcent and expectorant for cough, sore throat, bronchitis, and asthma. The flavonoids reduce inflammation in the airway mucosa, the saponins thin and mobilize mucus, and the sweetness coats and soothes the throat. Licorice is one of the few herbs traditionally used as a daily tea for chronic dry cough.

Antiviral activity has been documented against several respiratory viruses in laboratory studies. While clinical evidence in human respiratory infection is limited, the long traditional record and favorable mechanism support its inclusion in formulas for cough and bronchitis.

Back to Table of Contents

Antiviral Activity and Liver Support

Glycyrrhizin has documented antiviral activity in laboratory studies against herpes simplex virus, cytomegalovirus, and hepatitis viruses. In Japan, an intravenous glycyrrhizin preparation has been used for decades in chronic hepatitis B and C, with reductions in liver enzyme elevation and possible reduction of hepatocellular carcinoma risk in some long-term studies.

Oral licorice is unlikely to achieve the systemic levels of intravenous glycyrrhizin used in hepatitis trials, but topical licorice preparations (gels, creams) have been studied for herpes simplex outbreaks and aphthous (canker sore) ulcers with positive results.

Back to Table of Contents

Skin and Inflammatory Conditions

Topical licorice preparations have anti-inflammatory and skin-lightening properties. Glabridin, found in the root, inhibits tyrosinase (the enzyme that produces melanin) and is used in cosmetic preparations for hyperpigmentation, melasma, and post-inflammatory dark spots. Topical licorice extracts also reduce erythema (redness) in eczema and rosacea, with milder effects than topical corticosteroids and a much better safety profile for long-term use.

Back to Table of Contents

Forms and Preparations

• DGL (deglycyrrhizinated licorice) — chewable tablets typically 380-760 mg; the form practitioners use for gastrointestinal (GI) protection without cortisol-related side effects
• Whole licorice root tea — 1-3 g of dried root simmered in water; classical preparation with full constituent profile
• Standardized whole-root extract — often calibrated to glycyrrhizin content (commonly 4-12%); used for adrenal/cortisol support under clinical supervision
• Tinctures — 1:5 alcohol extracts; convenient but contain glycyrrhizin
• Glycyrrhizin-only preparations — highly concentrated; used in Asian hepatology under medical supervision
• Topical licorice extract — creams, gels, and serums for skin
• Licorice candy — variable in actual licorice content; some "licorice" candy is anise-flavored with little or no actual Glycyrrhiza; the ingredient list shows whether licorice root or extract is present

Back to Table of Contents

Doses Used and Official Limits

• DGL chewable — practitioners use 380-760 mg, chewed thoroughly 15-20 minutes before each meal and at bedtime, and regard it as suitable for long-term use because the glycyrrhizin has been removed
• Whole root for cough/throat — traditionally 1-3 g of dried root in tea two to three times daily, short-term (days to a few weeks); for its traditional use as an expectorant in cough with a cold, the EMA monograph lists 1.5-4.5 g of root in 150 ml of boiling water, 2-3 times a day, for adults
• Whole-root standardized extract for adrenal support — integrative protocols describe 100-300 mg twice daily of an extract delivering 75-150 mg of glycyrrhizin daily, with blood pressure (BP) and electrolytes monitored, for 4-12 weeks at a time; the official reference points are 100 mg of glycyrrhizin a day as the upper limit for regular intake (EC Scientific Committee on Food; JECFA) and 4 weeks as the EMA monograph's maximum for digestive use
• Topical preparations — amounts are given on each product's label
• Daily licorice candy — the EC Scientific Committee on Food's 100 mg-a-day glycyrrhizin limit corresponds to about 60 g of licorice sweets; many cases of pseudohyperaldosteronism have come from heavy licorice candy consumption

Back to Table of Contents

Cautions and Contraindications

• Hypertension — whole licorice and glycyrrhizin can raise blood pressure; the EMA monograph states that licorice medication is not recommended for people with high blood pressure, kidney disease, liver or heart and blood-vessel disorders, or low blood potassium, because they are more sensitive to its adverse effects; DGL is the form practitioners use in these conditions
• Heart failure and edema — can cause sodium and fluid retention worsening congestive heart failure; DGL lacks the glycyrrhizin responsible
• Hypokalemia — causes potassium loss; particularly dangerous when combined with thiazide and loop diuretics, leading to severe hypokalemia and cardiac arrhythmia; DGL lacks the glycyrrhizin responsible
• Pregnancy and breastfeeding — whole licorice associated with increased risk of preterm delivery and effects on fetal cortisol; the EMA monograph states that use is not recommended during pregnancy, in women who could become pregnant and are not using contraception, or while breastfeeding (glycyrrhizin is detectable in the breast milk of some women taking licorice, and its effect on infants is unknown)
• Children and teenagers — the EMA monograph states that use under 18 years of age is not recommended, because safety has not been established for lack of adequate data
• Drug interactions — digoxin (potassium loss potentiates toxicity), corticosteroids (potentiates effect), oral contraceptives (variable), antihypertensives (antagonizes effect); the EMA monograph lists diuretics, cardiac glycosides (such as digoxin), corticosteroids and stimulant laxatives among the medicines licorice is not to be used with, because they can worsen electrolyte imbalance, and notes that 300 mg of glycyrrhizin a day for 14 days modestly decreased the body's exposure to drugs broken down by the liver enzyme CYP3A4, such as midazolam and omeprazole
• Liver disease — the EMA monograph states that licorice medication is not recommended for people with liver disorders (paradoxically, glycyrrhizin is used therapeutically in some hepatology protocols)
• Duration of use — the EMA monograph sets 4 weeks as the maximum for digestive use of licorice root and links overdose cases to use beyond 4 weeks or to high intakes (water retention, low blood potassium, high blood pressure, heart-rhythm disorders, hypertensive encephalopathy); practitioners regard DGL as suitable for long-term use

Back to Table of Contents

Key Research Papers

The following PubMed search links provide curated entry points into the published clinical and mechanistic literature on Licorice (Glycyrrhiza glabra). Each link opens directly in PubMed at the National Library of Medicine.

1. DGL deglycyrrhizinated licorice for peptic ulcer — PubMed: DGL licorice peptic ulcer
2. Glycyrrhizin and cortisol metabolism — PubMed: glycyrrhizin cortisol 11-beta-HSD
3. Licorice for adrenal fatigue and HPA axis — PubMed: licorice HPA adrenal
4. Glycyrrhiza antiviral activity hepatitis HSV — PubMed: Glycyrrhiza antiviral hepatitis
5. Licorice and hypertension / pseudohyperaldosteronism — PubMed: licorice pseudohyperaldosteronism
6. Licorice for functional dyspepsia and gastritis — PubMed: licorice dyspepsia gastritis
7. Licorice safety and adverse effects review — PubMed: licorice safety review

External Authoritative Resources

1. NCCIH — Herbs at a Glance
2. MedlinePlus — Herbs and Supplements
3. European Medicines Agency — Liquorice root (Liquiritiae radix) herbal monograph and assessment report, Revision 1 (2026)
4. PubMed — All research on Glycyrrhiza glabra

Back to Table of Contents

Connections

• All Herbs
• Licorice Benefits Deep Dive
• Holy Basil
• Ashwagandha
• Rhodiola Rosea
• Cortisol Test
• Hypertension
• Hepatitis
• Potassium
• Asthma
• Adrenal Fatigue
• Peptic Ulcer Disease
• Reflux and Heartburn
• Liver Disease
• Anxiety
• Irritable Bowel Syndrome
• Small Intestinal Bacterial Overgrowth
• Gut Healing
• Ginger
• Gastroesophageal Reflux Disease
• Mullein
• Chen Pi (Aged Tangerine Peel) — aged citrus peel used to keep tonic formulas from causing bloating
• White Peony Root (Bai Shao) — source of Total Glucosides of Paeony, an approved rheumatoid-arthritis drug in China
• Codonopsis (Dang Shen) — the gentle, non-stimulant qi tonic used in place of ginseng
• Atractylodes (Bai Zhu) — the spleen-qi and digestion tonic paired with it in the classical Four Gentlemen formula
• Nhan Tran (Adenosma caeruleum) — Vietnam's everyday liver tea, and the species confusion surrounding it
• Conditions on this site that reference this page: Rosacea · Barrett's Esophagus · Gastritis · Sore Throat · Arrhythmia · Heart Failure · Canker Sores (Aphthous Ulcers) · Herpes Simplex

Back to Table of Contents

×

Featured Videos