Gan Cao
StarGlycyrrhiza uralensis Fisch.
Synonyms: Glycyrrhiza uralensis Fisch. ex DC., Liquiritia uralensis (Fisch.) Moench
☯ TCM Properties
Tonifies the Spleen and augments Qi; Moistens the Lungs, resolves Phlegm and stops coughing; Moderates spasms and alleviates pain; Clears Heat and relieves Fire toxicity; Moderates and harmonizes the harsh properties of other herbs
Traditional Chinese Uses
Gan Cao (licorice root) is the most widely used herb in all of Chinese medicine — its mild, sweet flavor and neutral character make it an ideal harmonizer that both strengthens Spleen and Lung Qi and mediates the interactions between other herbs in a formula. It stops cough, clears Heat toxin for sore throats and abscesses, relieves spasmodic pain in the extremities and abdomen, and modifies the harsh or toxic properties of other herbs. Honey-frying enhances its tonic action. It is the standard formula-harmonizing herb in TCM.
Western Herbalism Properties
Used In Formulas (25)
Gallery
Botanical Description
Glycyrrhiza uralensis is a perennial herb in the pea family (Fabaceae), growing from a stout, woody, deep-reaching taproot and spreading rhizomes. Erect, branched or unbranched stems reach 30–70 cm, occasionally to 120 cm, and are glandular and finely downy. The leaves are alternate and pinnately compound with 7–17 oval to lance-shaped leaflets. Small pale purple to violet pea-like flowers are borne in dense axillary spikes in mid to late summer, followed by oblong, curved, glandular-hairy pods. The medicinal part is the dried root and rhizome — cylindrical, 10–30 cm long and 1–2 cm thick, brownish-grey and longitudinally wrinkled outside, pale yellow and fibrous within — which is rich in glycyrrhizin and provides the herb Gan Cao.
Dry, sunny grasslands, sandy plains, and hillsides across the temperate steppe of northern China, Mongolia, and Central Asia.
Glycyrrhiza uralensis is widely distributed across the temperate steppe of northern China, Mongolia and Central Asia. Heavy wild harvesting for medicine has led to local depletion and desertification concerns in parts of its range, and it is increasingly cultivated to reduce pressure on wild stands.
Active Constituents
Glycyrrhizin (glycyrrhizic acid)
Triterpenoid saponinConcentration: ~2–9% of dried root
The principal sweet-tasting saponin (roughly 50× sweeter than sucrose) and the pharmacopoeial marker compound. Anti-inflammatory, antiviral and hepatoprotective. Hydrolysed in the gut to 18β-glycyrrhetinic acid, its active metabolite.
18β-Glycyrrhetinic acid
Triterpenoid aglyconeConcentration: Metabolite of glycyrrhizin
Active metabolite responsible for much of licorice's activity. Inhibits 11β-hydroxysteroid dehydrogenase type 2, slowing cortisol breakdown — the mechanism behind licorice's corticosteroid-like effects and, in excess, pseudoaldosteronism.
Liquiritin / liquiritigenin
Flavanone glycoside / aglyconeConcentration: Major flavonoids
Flavonoids credited with antitussive, expectorant, antispasmodic and antioxidant actions. Liquiritin is a pharmacopoeial quality marker alongside glycyrrhizin.
Isoliquiritigenin
ChalconeConcentration: Minor
Antioxidant and antispasmodic chalcone; studied for oestrogenic and anti-tumour activity in vitro.
Licochalcone A
ChalconeConcentration: Characteristic of G. inflata
Antimicrobial and anti-inflammatory chalcone; a chemotaxonomic marker distinguishing G. inflata from other licorice species.
Glabridin
IsoflavanConcentration: Characteristic of G. glabra
Antioxidant isoflavan and tyrosinase inhibitor (skin-lightening interest). Found mainly in G. glabra rather than G. uralensis.
⚠ Drug Interactions
Digoxin / cardiac glycosides
Glycyrrhizin-induced potassium loss (pseudoaldosteronism) sensitises the myocardium to cardiac glycosides.
Clinical note: Hypokalaemia can precipitate serious, potentially fatal arrhythmias. Avoid concurrent use, or monitor serum potassium and digoxin closely.
Loop & thiazide diuretics
Additive potassium depletion — both licorice and these diuretics lower serum potassium.
Clinical note: Risk of significant hypokalaemia (muscle weakness, cramps, arrhythmia). Avoid or monitor electrolytes.
Corticosteroids
Glycyrrhetinic acid inhibits 11β-HSD2, slowing cortisol inactivation and potentiating corticosteroid effects.
Clinical note: May intensify sodium/water retention, hypertension and hypokalaemia. Use cautiously with systemic steroids.
Antihypertensives
Licorice raises blood pressure through pseudoaldosteronism, opposing antihypertensive therapy.
Clinical note: Can reduce the efficacy of blood-pressure medication and worsen control. Avoid in uncontrolled hypertension.
Warfarin
Some evidence that licorice increases warfarin clearance, potentially lowering INR.
Clinical note: Limited data. Monitor INR if licorice is started or stopped.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| Decoction (raw Gan Cao) | 3–10 g | Daily, in divided doses | — | Adult |
Standard daily range. The Chinese Pharmacopoeia (2020) gives 2–10 g; Bensky's Materia Medica gives 1.5–9 g. When Gan Cao is used only to harmonize a formula, 1–2 g is sufficient. |
| Decoction (high dose, short-term) | 15–30 g | Daily | Short courses only | Adult |
Larger doses are used for clearing Fire toxicity (e.g. sore throat, drug/food toxicity) or acute spasmodic pain. Prolonged high-dose use risks pseudoaldosteronism (hypertension, hypokalaemia, oedema) and should be monitored. |
| Honey-fried (Zhi Gan Cao) | 3–9 g | Daily | — | Adult |
The honey-fried form is warmer and more tonifying; it is the form used to tonify Spleen and Heart Qi and to restore the pulse (e.g. in Zhi Gan Cao Tang / Regulate the Middle Decoction). |
Preparation Methods
Raw Gan Cao decoction
Parts: root, rhizome
Dried, unprocessed root and rhizome sliced and decocted with the other formula ingredients. Favoured for clearing Heat, resolving toxicity and moistening the Lung.
Honey-fried (Zhi Gan Cao)
Parts: root, rhizome
Sliced root stir-fried with honey until golden and no longer sticky. Processing warms the herb and enhances its Qi- and Blood-tonifying, pulse-restoring action.
Powder / granule
Parts: root, rhizome
Milled to powder or prepared as a concentrated granule for direct dosing where decoction is impractical.
Clinical Studies
Chemical analysis of the Chinese herbal medicine licorice (Gan-Cao): An update review
Comprehensive 2009–2022 review of licorice chemistry, quality evaluation, drug metabolism and pharmacokinetics; catalogues the triterpenoid saponins and flavonoids underlying its activity.
An Extract of Glycyrrhiza glabra (GutGard) Alleviates Symptoms of Functional Dyspepsia: A Randomized, Double-Blind, Placebo-Controlled Study
A standardised low-glycyrrhizin licorice extract significantly reduced functional-dyspepsia symptom scores versus placebo over 30 days, with good tolerability.
References
- Bensky D, Clavey S, Stöger E. Chinese Herbal Medicine: Materia Medica . 3rd ed. Seattle: Eastland Press (2004)
- Chinese Pharmacopoeia Commission. Glycyrrhizae Radix et Rhizoma . Pharmacopoeia of the People's Republic of China, Vol. I (2020)
- Shang Z, Liu C, Qiao X, Ye M. Chemical analysis of the Chinese herbal medicine licorice (Gan-Cao): An update review . Journal of Ethnopharmacology 299:115686 (2022) [DOI]
- Raveendra KR, et al.. An Extract of Glycyrrhiza glabra (GutGard) Alleviates Symptoms of Functional Dyspepsia: A Randomized, Double-Blind, Placebo-Controlled Study . Evidence-Based Complementary and Alternative Medicine 2012:216970 (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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