What is glycyrrhizin and what does it do in the body?

Glycyrrhizin is a triterpenoid saponin comprising 2–15% of dried licorice root (Glycyrrhiza glabra/uralensis) by weight and is responsible for licorice's characteristic sweetness (approximately 50 times sweeter than sucrose) and most of its pharmacological effects. After oral ingestion, gut bacteria hydrolyze it to 18β-glycyrrhetinic acid (GA), which inhibits 11β-hydroxysteroid dehydrogenase type 2, modulates CYP enzyme activity in the liver, suppresses NF-κB-driven inflammation, and exerts antiviral effects against pathogens including hepatitis B, hepatitis C, and HIV in vitro.

Is glycyrrhizin safe to take daily, and what are the risks?

Glycyrrhizin is considered unsafe at chronic daily intakes exceeding 100 mg due to the risk of pseudoaldosteronism—a cortisol-mimicking syndrome characterized by sodium retention, hypokalemia, hypertension, and edema caused by inhibition of the enzyme 11β-HSD2. The European Medicines Agency advises limiting daily glycyrrhizin consumption from all sources (supplements, candy, foods) to below this threshold; individuals with hypertension, heart disease, kidney disease, or those taking diuretics, corticosteroids, or anticoagulants face amplified risks and should avoid glycyrrhizin-containing products without medical supervision.

What is the difference between glycyrrhizin and DGL (deglycyrrhizinated licorice)?

Deglycyrrhizinated licorice (DGL) is a processed form of licorice root extract from which glycyrrhizin has been removed (typically to less than 2% residual content), eliminating the pseudoaldosteronism risk associated with 11β-HSD2 inhibition. DGL retains the mucoprotective flavonoids—including liquiritin and liquiritigenin—that stimulate mucus secretion and reduce gastric inflammation, making it the preferred form for treating peptic ulcers and GERD; standard DGL dosing is 380–760 mg chewed 20 minutes before meals, 2–3 times daily.

Does glycyrrhizin have antiviral effects against HIV or hepatitis?

In vitro studies have demonstrated that glycyrrhizin inhibits HIV replication and induces growth arrest in HIV-infected cells without significant cytotoxicity to host cells, suggesting a favorable therapeutic index in cell culture models; however, no human clinical trial data confirm antiviral efficacy in HIV-positive individuals. For viral hepatitis, the strongest clinical evidence involves intravenous glycyrrhizin (as the Japanese formulation SNMC) in chronic hepatitis C patients, where long-term treatment reduced serum aminotransferases and improved liver histology in observational cohorts, with some data suggesting reduced progression to hepatocellular carcinoma, though controlled RCT evidence is limited.

Can glycyrrhizin be used during pregnancy?

Glycyrrhizin is generally contraindicated during pregnancy due to its corticosteroid-like hormonal effects via 11β-HSD2 inhibition, which can alter fetal cortisol exposure and potentially stimulate uterine contractions. At least one prospective observational cohort study found that regular licorice consumption during pregnancy was associated with adverse cognitive and behavioral outcomes in offspring, attributed to fetal overexposure to active glucocorticoids; pregnant women should avoid licorice-containing products providing more than minimal glycyrrhizin and consult a healthcare provider before using any licorice-based supplement.

Does glycyrrhizin interact with blood pressure medications or diuretics?

Glycyrrhizin can increase sodium retention and potassium depletion, which may reduce the effectiveness of antihypertensive medications and potentiate the effects of diuretics, potentially leading to electrolyte imbalances. Individuals taking blood pressure medications, loop diuretics, or thiazide diuretics should monitor electrolyte levels and consult their healthcare provider before using glycyrrhizin supplements. This interaction is particularly relevant for those with hypertension or heart conditions, as mineral dysregulation could complicate their management.

What clinical evidence supports glycyrrhizin for liver disease or viral hepatitis?

Intravenous Stronger Neo-Minophagen C (SNMC), a standardized glycyrrhizin formulation, has demonstrated reduced hepatic inflammation and aminotransferase levels in multiple clinical trials for chronic hepatitis C and B in Japan and other countries. Glycyrrhizin's hepatoprotective mechanism involves suppressing NF-κB-mediated inflammation and enhancing detoxification through upregulation of cytochrome P450 1A1 and glutathione S-transferase enzymes. However, oral glycyrrhizin supplements have less robust clinical evidence compared to the intravenous formulation, and patients with active liver disease should use them under medical supervision.

How much glycyrrhizin is safe to take, and what happens with long-term daily use?

The WHO recommends a maximum daily intake of 100 mg glycyrrhizin (roughly equivalent to 1–2 grams of licorice root extract), though some sources suggest 75–100 mg as a safer threshold for extended use. Long-term daily consumption above these levels increases the risk of pseudoaldosteronism (sodium retention, potassium loss, hypertension, and edema), with symptoms typically emerging after 4–6 weeks of sustained high-dose use. Duration of use should ideally be limited to 4–6 weeks unless under medical supervision, and baseline blood pressure and electrolyte status should be established before beginning supplementation.

Glycyrrhizin

Glycyrrhizin is a triterpenoid saponin that exerts anti-inflammatory, antiviral, and hepatoprotective effects primarily through inhibition of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), suppression of NF-κB signaling, and its gut-hydrolyzed aglycone 18β-glycyrrhetinic acid (GA) modulating CYP enzyme activity and apoptotic pathways. In chronic hepatitis C patients, long-term intravenous glycyrrhizin administration significantly reduced serum aminotransferases and improved liver histology, with observational data suggesting a reduction in hepatocellular carcinoma progression, though large randomized controlled trial data with standardized effect sizes remain limited.

Category: Compound Evidence: 1/10 Tier: Preliminary

Origin & History

Glycyrrhizin is the principal bioactive triterpenoid saponin extracted from the roots and rhizomes of licorice species, primarily Glycyrrhiza glabra (Spanish/Italian licorice) and Glycyrrhiza uralensis (Chinese licorice), which are native to the Mediterranean basin, Central Asia, and China. The plants thrive in well-drained, deep alluvial soils in temperate to semi-arid climates, often cultivated along riverbanks and in floodplains across Iran, Turkey, Uzbekistan, and the Xinjiang region of China. Commercial extraction typically involves hydromethanolic or aqueous processing of three- to four-year-old dried roots, where glycyrrhizin content ranges from 2–15% of dry root weight depending on species, ecotype, and harvest conditions.

Historical & Cultural Context

Licorice root has one of the longest documented medicinal histories of any botanical, with records of use in ancient Egypt dating back over 3,000 years, where it was prepared as a sweet beverage for pharaohs and included in tomb provisions for the afterlife, including those of Tutankhamun. In Traditional Chinese Medicine (TCM), Glycyrrhiza uralensis root ('Gan Cao', meaning 'sweet herb') has served for over 2,000 years as a primary harmonizing herb appearing in the majority of classical formulas—including the Shennong Bencao Jing (Divine Farmer's Classic)—where it was used to treat coughs, throat inflammation, peptic ulcers, liver disease, and as a detoxifying adjuvant to moderate the toxicity of other herbs. Ancient Greek and Roman physicians, including Theophrastus and Dioscorides, documented its use for respiratory conditions, thirst quenching, and wound healing under the name 'glykyrrhiza' (from Greek glykys: sweet + rhiza: root), and Scythian warriors reputedly used it to sustain energy and suppress hunger on long campaigns. In medieval European herbalism and Islamic medicine, including the works of Ibn Sina (Avicenna), licorice was prescribed for chest disorders, inflammatory conditions, and urinary complaints, and it later became a fixture of European confectionery and pharmaceutical traditions in England, Italy, and the Netherlands.

Health Benefits

- **Hepatoprotection**: Glycyrrhizin reduces hepatic inflammation by suppressing NF-κB-driven cytokine release and downregulating CYP2E1, while its metabolite 18β-glycyrrhetinic acid (GA) upregulates CYP1A1 and glutathione S-transferase (GST) activities to detoxify hepatotoxins including aflatoxins; clinical use in Japan as intravenous Stronger Neo-Minophagen C (SNMC) has demonstrated reduced aminotransferases in viral hepatitis patients.
- **Antiviral Activity**: Glycyrrhizin inhibits viral replication across multiple pathogens including hepatitis B (by suppressing HBsAg transport), hepatitis C, influenza, and HIV; polysaccharide fractions and glycyrrhizin analogs interrupt viral entry and replication, and in vitro studies show growth inhibition of HIV without concurrent cytotoxicity to host cells.
- **Anti-Inflammatory Effects**: GA mimics corticosteroid action by inhibiting 11β-HSD2, allowing cortisol accumulation at mineralocorticoid receptors, and independently suppresses phospholipase A2 and prostaglandin synthesis; a 2019 review noted glycyrrhizin-containing extracts relieved asthma symptoms through this anti-inflammatory mechanism with a favorable side-effect profile relative to conventional therapies.
- **Anticancer and Pro-Apoptotic Properties**: Glycyrrhizin and its metabolite GA induce apoptosis in tumor cells via mitochondrial permeability transition pore opening, Bcl-2 phosphorylation, and G2/M cell cycle arrest; the related licorice constituent licocoumarone demonstrates analogous pro-apoptotic effects in leukemia U937 cells in vitro.
- **Anticoagulant and Antiplatelet Effects**: Glycyrrhizin directly inhibits thrombin activity, prolonging clotting time and suppressing thrombin-induced platelet aggregation in a selective manner that does not interfere with PAF- or collagen-mediated aggregation pathways, suggesting potential utility in thrombotic conditions.
- **Antioxidant Activity**: Associated isoflavones such as glabridin and hispaglabridin A in licorice root extracts scavenge reactive oxygen species and inhibit lipid peroxidation; the related compound echinatin activates the Nrf2 antioxidant response pathway, attenuating CCl4-induced oxidative liver damage in murine models at doses of 5–10 mg/kg (intraperitoneal).
- **Antimicrobial and Antiulcer Actions**: Licorice bioactives including glycyrrhizin display activity against H. pylori and other gastrointestinal pathogens; deglycyrrhizinated licorice (DGL) preparations, which retain flavonoid content without glycyrrhizin, are specifically used for peptic ulcer management by stimulating mucus secretion and reducing mucosal inflammation without systemic endocrine side effects.

How It Works

Glycyrrhizin is hydrolyzed in the gastrointestinal tract by bacterial enzymes to its bioactive aglycone 18β-glycyrrhetinic acid (GA), which inhibits 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), the enzyme responsible for converting active cortisol to inactive cortisone in kidney and vascular tissues; this results in cortisol accumulation at mineralocorticoid receptors, producing sodium retention, potassium excretion, and hypertension at high doses, but also potent anti-inflammatory corticosteroid-like effects. At the molecular level, GA downregulates CYP2E1 expression while upregulating CYP1A1 and glutathione S-transferase (GST), enhancing hepatic detoxification capacity; it also modulates the transcription factor AP-1, activating it in baseline conditions while inhibiting TPA-induced AP-1 activation, thereby influencing oncogene expression and cell proliferation. Glycyrrhizin exerts direct antiviral activity by interfering with viral protein-host cell membrane interactions, suppressing hepatitis B surface antigen (HBsAg) transport, and disrupting influenza virus replication via immunostimulatory polysaccharide-mediated macrophage activation. Pro-apoptotic effects in cancer cell lines are mediated through mitochondrial permeability transition, altered Bcl-2 family protein phosphorylation states, and induction of G2/M cell cycle arrest, while thrombin inhibition proceeds through direct binding that selectively attenuates thrombin-induced but not PAF- or collagen-induced platelet aggregation.

Scientific Research

The clinical evidence base for glycyrrhizin is predominantly preclinical, comprising in vitro cell culture studies and rodent model experiments, with a smaller body of observational and non-randomized clinical data, particularly from Japan where intravenous glycyrrhizin (as Stronger Neo-Minophagen C, SNMC: 0.2% glycyrrhizin, 0.1% cysteine, 2% glycine) has been used for decades in chronic viral hepatitis management. Long-term SNMC treatment in chronic hepatitis C cohorts demonstrated reductions in serum ALT and AST levels and improvements in liver histology, with retrospective analyses suggesting a reduced incidence of hepatocellular carcinoma (HCC) in treated patients, though these studies were largely non-randomized and subject to selection bias, limiting causal interpretation. A 2019 systematic review identified anti-asthmatic properties of glycyrrhizin-containing extracts but did not provide standardized effect sizes or randomized trial data, and most antiviral claims including anti-HIV growth inhibition remain at the in vitro stage without peer-reviewed human RCT confirmation. The overall evidence must be characterized as preliminary-to-moderate: mechanistically compelling and supported by robust preclinical data and select clinical observational findings, but lacking the large, well-controlled, double-blind RCTs needed to establish definitive clinical efficacy and dose-response relationships.

Clinical Summary

The most clinically substantiated application of glycyrrhizin is in chronic viral hepatitis, particularly hepatitis C, where Japanese clinical practice and associated observational studies using intravenous SNMC formulations reported normalization or significant reduction of serum aminotransferases and histological improvement over multi-year treatment periods, with some retrospective cohort data suggesting a delay in HCC progression. However, these hepatitis findings derive largely from open-label or observational designs without blinded placebo controls, and no large multicenter RCT has been published with standardized sample sizes and pre-registered outcomes. Anti-HIV activity in vitro—specifically growth inhibition without cytotoxicity to host cells—has been replicated across multiple cell culture studies, but no human clinical trial data exist to confirm antiviral efficacy in HIV-infected individuals. For antimalarial indications cited in traditional and emerging literature, mechanistic and in vivo data are even more limited, and no human clinical endpoints have been formally evaluated in registered trials.

Nutritional Profile

Glycyrrhizin itself is a pure triterpenoid saponin compound (molecular formula C₄₂H₆₂O₁₆, MW ~822.9 g/mol) and does not contribute macronutrients in supplemental doses; however, whole licorice root and its extracts contain a diverse phytochemical matrix. The root contains 2–15% glycyrrhizin (glycyrrhizic acid) and its aglycone 18β-glycyrrhetinic acid (GA) upon hydrolysis; 1–3% flavonoids including liquiritin, liquiritigenin, isoliquiritin, glabridin (up to 0.1% in root), and hispaglabridin A and B; isoflavones and retrochalcones; triterpene saponins beyond glycyrrhizin; phenolic acids; polysaccharides (6–10%) with immunostimulatory activity; and coumarins. Bioavailability of oral glycyrrhizin is substantially limited by intestinal bacterial hydrolysis to GA before systemic absorption, with GA reaching peak plasma concentrations approximately 8–24 hours post-ingestion due to enterohepatic recirculation; intravenous glycyrrhizin bypasses this limitation entirely. Glabridin and other lipophilic isoflavones exhibit significantly higher membrane permeability and bioavailability than glycyrrhizin itself and may account for antioxidant and skin-protective effects at physiologically achievable concentrations.

Preparation & Dosage

- **Intravenous Glycyrrhizin (SNMC, clinical)**: Standard Japanese clinical dosing is 40–100 mL of SNMC (containing 0.2% glycyrrhizin) administered intravenously 2–7 times per week for chronic hepatitis; this route bypasses gut hydrolysis and achieves direct systemic exposure.
- **Oral Root Extract (standardized)**: Typical supplemental doses of standardized licorice root extract range from 400–1,600 mg/day, often standardized to 4–10% glycyrrhizin content; total glycyrrhizin intake should remain below 100 mg/day to minimize pseudoaldosteronism risk.
- **Deglycyrrhizinated Licorice (DGL)**: DGL tablets or chewable lozenges (typically 380–760 mg, taken 20 minutes before meals, 2–3 times daily) are used specifically for peptic ulcer and GERD management; glycyrrhizin is removed to eliminate hypertensive and hypokalemic risk while retaining mucoprotective flavonoids.
- **Traditional Tea/Decoction**: Dried licorice root (2–5 g) simmered in 250 mL water for 10–15 minutes; consumed 1–3 times daily in traditional Chinese and Ayurvedic formulations, often combined with other herbs.
- **Hydromethanolic/Acetone Extracts (research grade)**: Used in preclinical and in vitro studies; 70% methanol extractions yield highest glycyrrhizin concentrations for analytical and pharmacological characterization.
- **Topical Formulations**: Glycyrrhizin and GA-based creams (0.5–2% concentration) applied to skin for anti-inflammatory and skin-lightening effects; not subject to systemic dosing concerns at these concentrations.
- **Timing Note**: Oral glycyrrhizin should be taken with food to moderate absorption rate; chronic daily use beyond 4–6 weeks at doses exceeding 100 mg glycyrrhizin requires blood pressure and serum potassium monitoring.

Synergy & Pairings

Glycyrrhizin is classically combined with cysteine and glycine in the intravenous SNMC formulation, where glycine provides direct hepatocytoprotective and anti-inflammatory support while cysteine serves as a glutathione precursor, enhancing antioxidant defenses synergistically with glycyrrhizin's CYP1A1/GST upregulation in hepatic detoxification. In TCM formulations, licorice root (Gan Cao) is routinely paired with astragalus (Astragalus membranaceus) and ginseng (Panax ginseng) to modulate immune function, where the immunostimulatory polysaccharides from all three herbs act additively on macrophage activation while glycyrrhizin's cortisol-potentiating effects moderate excessive immune responses. For antiviral applications, glycyrrhizin has been studied in combination with zinc salts and quercetin, as zinc ionophore activity of quercetin may complement glycyrrhizin's membrane-disrupting antiviral mechanisms, though robust clinical synergy data remain at the preclinical stage.

Safety & Interactions

The primary dose-dependent safety concern with glycyrrhizin is pseudoaldosteronism—a syndrome of sodium retention, potassium depletion, hypertension, and edema resulting from 11β-HSD2 inhibition by GA—which has been documented at chronic daily intakes exceeding 50–100 mg glycyrrhizin; the European Medicines Agency and health authorities in multiple countries advise limiting licorice consumption to avoid this threshold. Drug interactions of clinical significance include: potentiation of antihypertensive drug failure (antagonism of ACE inhibitors, diuretics, beta-blockers), enhancement of corticosteroid effects (additive 11β-HSD2 inhibition), potential potentiation of anticoagulants such as warfarin due to glycyrrhizin's thrombin-inhibitory activity, and risk of digitalis toxicity amplified by glycyrrhizin-induced hypokalemia. Contraindications include pre-existing hypertension, heart failure, chronic kidney or liver disease, hypokalemia, and pregnancy (hormonal effects and potential stimulation of premature labor have been documented in observational data; regular consumption during pregnancy has been associated with adverse fetal neurodevelopmental outcomes in at least one prospective cohort study). Deglycyrrhizinated licorice (DGL) preparations eliminate pseudoaldosteronism risk and are generally well tolerated, making them the preferred form for prolonged oral use in gastrointestinal applications.