Licorice
StarGlycyrrhiza glabra
Synonyms: Glycyrrhiza glabra var. brachycarpa, Glycyrrhiza glandulifera var. parviflora, Glycyrrhiza officinalis, Glycyrrhiza pallida, Glycyrrhiza michajloviana, Glycyrrhiza glandulifera, Glycyrrhiza glabra var. hispidula, Glycyrrhiza glabra subsp. glandulifera, Glycyrrhiza glabra var. echinata, Glycyrrhiza glabra var. asperula, Glycyrrhiza alalensis, Glycyrrhiza hirsuta, Glycyrrhiza brachycarpa, Glycyrrhiza glabra var. pubescens, Glycyrrhiza hirsuta var. echinata, Glycyrrhiza hirsuta var. glandulifera, Glycyrrhiza glabra var. laxifoliolata, Glycyrrhiza glabra var. caduca, Liquiritia officinarum, Liquiritia officinalis, Glycyrrhiza glabra var. glandulosa, Glycyrrhiza violacea, Glycyrrhiza glabra var. violacea, Glycyrrhiza glabra var. glandulifera, Glycyrrhiza nadezhinae, Glycyrrhiza laevis, Glycyrrhiza vulgaris, Glycyrrhiza echinata, Glycyrrhiza alaschanica
Western Herbalism Properties
Traditional Uses
Licorice root is one of the most widely used medicinal plants across the world's healing traditions. In the Cherokee pharmacopoeia the root was used for coughs, as an expectorant, for asthma and other respiratory complaints, and for hoarseness and throat troubles (Hamel & Chiltoskey, 1975), and a compounded preparation containing the (non-native) root was used by the Meskwaki as a gynecological remedy for "female trouble" (Smith, 1928). In Traditional Chinese Medicine the root ("Gan Cao") is among the most frequently prescribed herbs, used to harmonize formulas, moisten the lungs and ease cough and sore throat, and to tonify the spleen and qi. In Ayurveda the root ("Yashtimadhu" or "Mulethi") is a classic demulcent and rejuvenative used for cough, hyperacidity, ulcers and as a soothing throat remedy. Across Middle Eastern, European and Mediterranean folk medicine licorice has long been employed as a sweet expectorant cough remedy and a soothing treatment for gastric ulcers and inflamed mucous membranes (Foster & Duke, 2000; Wikipedia).
Gallery
Botanical Description
Glycyrrhiza glabra (licorice) is a perennial herb of the legume family growing 1-1.5 m tall from a deep, branching woody taproot and long horizontal stolons that yield the sweet licorice of commerce. The erect stems bear alternate, pinnately compound leaves with 9-17 ovate to oblong, slightly sticky leaflets. The pea-like flowers are small, pale blue to violet or whitish, borne in loose erect axillary racemes. The fruit is a flattened, oblong, glabrous or slightly glandular legume pod 2-3 cm long containing several reniform seeds. Native to southern Europe, the Mediterranean, the Middle East and western to central Asia, it is widely cultivated for its roots and rhizomes, which are rich in the intensely sweet saponin glycyrrhizin together with flavonoids and coumarins.
Active Constituents
Glycyrrhizin (glycyrrhizic acid)
Triterpenoid saponinConcentration: 2-9% of dried root
The principal sweet-tasting saponin, roughly 50 times sweeter than sucrose. Its aglycone 18β-glycyrrhetinic acid inhibits 11β-hydroxysteroid dehydrogenase type 2 in the kidney, prolonging cortisol action at the mineralocorticoid receptor. This underlies both the anti-inflammatory, mucosal-protective and expectorant actions and the dose-limiting pseudohyperaldosteronism (sodium retention, potassium loss, hypertension).
18β-Glycyrrhetinic acid
Triterpenoid aglyconeConcentration: Metabolite (formed by gut flora)
Active hydrolysis product of glycyrrhizin generated by intestinal bacteria. Responsible for much of the systemic anti-inflammatory, hepatoprotective and mineralocorticoid-like activity, and is the moiety directly inhibiting 11β-HSD2.
Glabridin
Isoflavan (prenylated flavonoid)Concentration: Up to ~1% (marker of G. glabra vs G. uralensis)
A lipophilic isoflavan characteristic of G. glabra with antioxidant, anti-inflammatory, tyrosinase-inhibiting (skin-lightening) and estrogen-modulating activity. It also inhibits several cytochrome P450 enzymes in vitro, a basis for potential herb-drug interactions.
Liquiritin / liquiritigenin
Flavanone glycoside / aglyconeConcentration: 1-2%
Major flavonoids contributing antioxidant, antispasmodic and mild antidepressant/anxiolytic effects in preclinical models; liquiritigenin is a selective estrogen receptor-β agonist.
Isoliquiritigenin
ChalconeConcentration: Trace-minor
A chalcone with documented antioxidant, aldose-reductase-inhibiting, anti-inflammatory and antispasmodic (gut smooth muscle relaxant) activity in experimental studies.
Glabrol / glabrene
Prenylated flavonoidsConcentration: Minor
Flavonoids contributing to the antimicrobial and phytoestrogenic profile of the flavonoid-rich fraction; glabrene shows estrogen-receptor binding.
Licochalcone A
RetrochalconeConcentration: Minor
Studied for antibacterial (including against Helicobacter and Staphylococcus), anti-inflammatory and anticancer activity in vitro.
⚠ Drug Interactions
Corticosteroids (e.g. hydrocortisone, prednisolone)
Glycyrrhetinic acid inhibits 11β-HSD2 and 5β-reductase, slowing cortisol/corticosteroid metabolism and adding a mineralocorticoid-like effect, so systemic and topical corticosteroid activity and adverse effects are augmented.
Clinical note: Avoid chronic high-dose licorice with corticosteroids; monitor blood pressure, potassium and edema.
Digoxin / cardiac glycosides
Licorice-induced hypokalemia sensitizes the myocardium to cardiac glycosides, increasing the risk of digoxin toxicity and arrhythmias even at therapeutic digoxin levels.
Clinical note: Avoid regular licorice use in patients on digoxin; monitor serum potassium.
Thiazide and loop diuretics
Both licorice (via mineralocorticoid effect) and potassium-wasting diuretics lower serum potassium, producing additive hypokalemia and its cardiac consequences.
Clinical note: Monitor potassium; counsel against high licorice intake.
Antihypertensive agents
Sodium and water retention from glycyrrhizin raises blood pressure and can antagonize antihypertensive therapy, including ACE inhibitors and ARBs.
Clinical note: Discourage regular licorice confectionery/tea in hypertensive patients.
CYP3A4 / P-glycoprotein substrates
Licorice flavonoids (glabridin, licochalcones) modulate several CYP450 isoforms and P-glycoprotein in vitro; clinical significance for individual drugs is not well established.
Clinical note: Use caution with narrow-therapeutic-index drugs during high-dose or prolonged licorice use.
Preparation Methods
Decoction / tea
Parts: Root, Stolon
Simmer 1-4 g of dried, shredded root in water for 10-15 minutes. Traditionally used as a demulcent for sore throat, cough and gastric complaints. Because of pseudohyperaldosteronism risk, prolonged daily use above roughly 2-4 g glycyrrhizin-containing root (or >100 mg glycyrrhizin/day) should be avoided; it is contraindicated in hypertension, heart or kidney disease, hypokalemia and pregnancy.
Deglycyrrhizinated licorice (DGL)
Parts: Root
Commercial extract with glycyrrhizin removed to below ~3%, taken as chewable tablets before meals for gastric/duodenal mucosal support. Removing glycyrrhizin greatly reduces the risk of hypertension and hypokalemia, allowing longer-term use.
Standardized flavonoid extract
Parts: Root
Low-glycyrrhizin, flavonoid-standardized extracts (e.g. glabridin-standardized) are used at 75-150 mg/day for dyspepsia and reflux, as in controlled trials.
Topical preparation
Parts: Root extract
Glycyrrhetinic-acid or glabridin-containing creams/gels are applied for eczema, aphthous ulcers and hyperpigmentation.
Clinical Studies
An Extract of Glycyrrhiza glabra (GutGard) Alleviates Symptoms of Functional Dyspepsia: A Randomized, Double-Blind, Placebo-Controlled Study
Fifty patients with functional dyspepsia received a flavonoid-rich G. glabra extract (GutGard, 75 mg twice daily) or placebo for 30 days. The extract produced a significant reduction in total symptom scores and Nepean Dyspepsia Index and improved global assessment of efficacy versus placebo, and was well tolerated.
Clinical Risk Factors of Licorice-Induced Pseudoaldosteronism Based on Glycyrrhizin-Metabolite Concentrations: A Narrative Review
Reviews the mechanism and clinical risk factors of licorice-induced pseudohyperaldosteronism, identifying 18β-glycyrrhetyl-3-O-sulfate as the major human metabolite and highlighting dose, duration, age, hypoalbuminemia and concomitant diuretics as risk factors for hypokalemia and hypertension.
Historical Texts
Dioscorides, De Materia Medica
1st century CECulpeper's Complete Herbal
17th century (England)Ayurvedic materia medica (Yashtimadhu)
Classical Indian medicineReferences
- Yoshino T, Yanagawa T, Watanabe K, et al.. Clinical Risk Factors of Licorice-Induced Pseudoaldosteronism Based on Glycyrrhizin-Metabolite Concentrations: A Narrative Review . Frontiers in Nutrition (2021) [DOI]
- Raveendra KR, Jayachandra, Srinivasa V, et al.. An Extract of Glycyrrhiza glabra (GutGard) Alleviates Symptoms of Functional Dyspepsia . Evidence-Based Complementary and Alternative Medicine (2012) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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