Herbal Monograph
Licorice
Glycyrrhiza glabra L.
Fabaceae (Leguminosae)
The great harmonizer -- the most widely used herb in traditional Chinese medicine, with critical drug interactions every practitioner must know.
Overview
Plant Description
Perennial herbaceous legume, 1-2 m tall, with an extensive root and stolon system. Root is long, cylindrical, branching, up to 1-2 cm in diameter, with a brown to grayish-brown cork externally and pale yellow fibrous interior with a characteristic sweet taste (approximately 50 times sweeter than sucrose due to glycyrrhizin). Stolons (horizontal underground stems) spread extensively, reaching 1-2 m in length, enabling vegetative propagation and making harvesting of wild populations environmentally significant. Stems erect, branching, slightly sticky due to glandular hairs (in var. glandulifera). Leaves alternate, odd-pinnate, 7-15 cm long, with 9-17 ovate to oblong leaflets (2-5 cm long), slightly sticky on the underside with glandular dots. Inflorescence an axillary raceme, 5-15 cm long, bearing numerous small (8-12 mm) papilionaceous flowers, pale blue to violet or lilac (occasionally whitish). Fruit a flattened, oblong-linear legume (pod), 2-3 cm long, containing 2-5 reniform (kidney-shaped) seeds. Root system can penetrate to 1-2 m depth with stolons spreading several meters laterally, making mature stands difficult to eradicate.
Habitat
Native to the Mediterranean region, southern Russia, and western Asia (Iran, Turkey, Iraq). Grows in deep, fertile, well-drained alluvial soils, particularly in river valleys, flood plains, and semi-arid steppes. Tolerates moderate salinity and alkaline soils (pH 6-8). Prefers full sun and warm, dry summers. Drought-tolerant once established due to deep root system. Found from sea level to approximately 1000 m altitude.
Distribution
Native range spans from the western Mediterranean (Spain, Italy) through southeastern Europe (Greece, Turkey) to Central and western Asia (Iran, Afghanistan, Turkmenistan, Uzbekistan, Kazakhstan, western China). Major commercial production: Turkey, Iran, China (primarily G. uralensis), Uzbekistan, Turkmenistan, Afghanistan, and Iraq. Naturalized in parts of India, Pakistan, and scattered locations in the Americas and Australia. Wild harvesting remains significant in Central Asian countries, raising sustainability concerns.
Parts Used
Root (Radix Glycyrrhizae)
Preferred: Dried root slices for decoction, powdered root, fluid extract, DGL (deglycyrrhizinated licorice) chewable tablets
The primary medicinal part. The root proper grows vertically and is the main taproot system. Contains the full spectrum of bioactive compounds including glycyrrhizin (triterpenoid saponin), flavonoids (liquiritigenin, glabridin, isoliquiritigenin), isoflavonoids, coumarins, and polysaccharides. Both peeled (cortex removed) and unpeeled forms are used medicinally. Peeled root is preferred in some traditions and pharmacopeias as it provides a more uniform product. The root is used in virtually all traditional systems worldwide and is the subject of the vast majority of clinical and pharmacological research.
Stolon (horizontal underground stem, also called runner or rhizome in some references)
Preferred: Dried slices for decoction, powdered, included in commercial root preparations
Stolons are used interchangeably with roots in most pharmacopeias and commercial preparations. They have a similar but not identical chemical profile to the root proper, typically with slightly lower glycyrrhizin content. Stolons are a major part of commercial licorice because the extensive lateral spreading system yields considerable harvestable material. In Chinese Pharmacopoeia, both roots and stolons (rhizomes) of Glycyrrhiza species are accepted as Gan Cao.
Key Constituents
Triterpenoid saponins
Glycyrrhizin and its metabolite glycyrrhetinic acid are the most pharmacologically important and clinically significant constituents. They are responsible for anti-inflammatory (via inhibition of prostaglandin E2, thromboxane A2, and modulation of glucocorticoid metabolism), antiviral (direct viricidal activity and immunomodulation), hepatoprotective, and immunomodulatory effects. They are also the source of the primary safety concern: pseudoaldosteronism from 11-beta-HSD2 inhibition. DGL (deglycyrrhizinated licorice) products have glycyrrhizin removed to below 3% to avoid mineralocorticoid effects while retaining other therapeutic constituents.
Flavonoids and isoflavonoids
The flavonoid fraction of licorice provides complementary therapeutic activity to the saponin fraction. Flavonoids contribute anti-inflammatory (via different pathways than glycyrrhizin), antispasmodic/spasmolytic, antioxidant, and phytoestrogenic effects. The flavonoid and isoflavonoid compounds are largely retained in DGL preparations, meaning DGL is not merely a 'depleted' product but retains significant bioactive constituents. Glabridin's SERM-like activity has attracted research interest for menopausal symptom management, though clinical evidence remains limited.
Coumarins
Coumarins are minor but pharmacologically contributing constituents. They participate in the overall antispasmodic and anti-inflammatory activity of licorice extracts.
Polysaccharides and other constituents
Polysaccharides contribute to immunomodulatory effects observed with aqueous extracts (decoctions, teas). The mucilaginous quality of licorice extracts derives in part from polysaccharides and contributes to the demulcent action. Asparagine content is nutritionally notable but therapeutically minor.
Herbal Actions
Soothes and protects irritated mucous membranes
One of licorice's most important traditional actions. The mucilaginous polysaccharides and saponin content provide a soothing, coating effect on mucous membranes of the gastrointestinal and respiratory tracts. This action underlies much of licorice's use for peptic ulcers, gastritis, sore throat, and respiratory catarrh. The demulcent property is retained in DGL preparations. Licorice is frequently included in herbal formulas specifically for its mucosal-protective and soothing properties, even when other herbs in the formula are the primary therapeutic agents.
[2, 19]Promotes the discharge of mucus from the respiratory tract
Promotes the secretion and expulsion of mucus from the respiratory tract. The saponin content (glycyrrhizin) stimulates mucus production in the bronchi while simultaneously reducing the viscosity of existing mucus, facilitating expectoration. This dual action makes licorice one of the most widely used herbs for productive and non-productive coughs. Commission E approved licorice for catarrh of the upper respiratory tract. Used in cough syrups and respiratory formulas across virtually all herbal traditions.
[1, 2, 19]Reduces inflammation
Multi-mechanism anti-inflammatory activity. Glycyrrhizin and glycyrrhetinic acid inhibit prostaglandin E2 and thromboxane A2 synthesis. Glycyrrhetinic acid potentiates endogenous cortisol activity by inhibiting 11-beta-HSD2, effectively increasing active cortisol availability at the tissue level. This 'cortisol-sparing' mechanism is a unique form of anti-inflammatory action among medicinal plants. Flavonoids (liquiritigenin, isoliquiritigenin) provide additional anti-inflammatory activity through COX-2 inhibition and NF-kB modulation. The combined saponin and flavonoid anti-inflammatory actions make licorice effective for both GI inflammation (ulcers, gastritis) and systemic inflammatory conditions.
[19, 20, 21]Relieves smooth muscle spasm
Relaxes smooth muscle, particularly in the gastrointestinal tract. Flavonoids (especially liquiritigenin and isoliquiritigenin) are the primary constituents responsible for spasmolytic activity, likely through phosphodiesterase inhibition and calcium channel modulation. Contributes to relief of intestinal cramping, colic, and bronchospasm. The combination of demulcent and antispasmodic actions makes licorice particularly effective for irritable conditions of the GI tract.
[2, 19]Helps the body adapt to stress and restore homeostasis
Supports adrenal function and modulates the hypothalamic-pituitary-adrenal (HPA) axis. The mechanism is primarily through inhibition of 11-beta-HSD2, which preserves cortisol activity and reduces the demand on the adrenal cortex for cortisol production. This makes licorice particularly relevant for individuals with adrenal fatigue or HPA axis dysfunction, though the term 'adaptogen' is used loosely here compared to classic adaptogens like Panax ginseng or Eleutherococcus. Some practitioners consider licorice's mechanism more accurately described as 'adrenal supportive' rather than truly adaptogenic. The adrenal-supportive action must be balanced against the risk of pseudoaldosteronism with prolonged or high-dose use.
[19, 20]Protects the liver from damage
Glycyrrhizin demonstrates liver-protective effects in multiple models. Stronger Neominophagen C (SNMC), an injectable glycyrrhizin preparation, has been used in Japan and parts of Asia for decades as a treatment for chronic hepatitis. Glycyrrhizin reduces serum transaminases (ALT, AST), inhibits hepatic inflammation, and demonstrates antifibrotic activity. Flavonoids contribute additional antioxidant protection in hepatocytes. The hepatoprotective mechanism involves both direct membrane-stabilizing effects and modulation of inflammatory/immune cascades in the liver.
[8, 20, 21]Kills or inhibits the growth of microorganisms
Demonstrated antibacterial activity against various pathogens including Helicobacter pylori, Staphylococcus aureus (including MRSA in some studies), Streptococcus mutans, and Candida species. Glabridin and other flavonoids contribute to antibacterial and antifungal activity. Glycyrrhizin demonstrates significant antiviral activity, particularly against enveloped viruses. In vitro activity demonstrated against hepatitis C virus, SARS-CoV, HIV, herpes simplex, influenza, and respiratory syncytial virus. The antiviral mechanism involves interference with viral adsorption and penetration, and stimulation of interferon-gamma production.
[10, 20, 21]Modulates and balances immune function
Complex immunomodulatory effects depending on dose and context. Glycyrrhizin enhances interferon-gamma production, activates natural killer cells, and modulates T-helper cell balance (promoting Th1 response in some contexts). Polysaccharides (glycyrrhizan GA) activate macrophages and complement system. At the same time, the anti-inflammatory cortisol-sparing effect can be immunosuppressive in certain pathways. This dual immunomodulatory profile (immune-enhancing in some pathways, anti-inflammatory/suppressive in others) is characteristic of licorice and contributes to its use in both immune-deficiency and autoimmune/inflammatory contexts in traditional practice.
[20, 21]Prevents or slows oxidative damage to cells
Flavonoids (glabridin, isoliquiritigenin, liquiritigenin) and isoflavonoids provide significant free radical scavenging activity. Glabridin is a particularly potent antioxidant, inhibiting LDL oxidation and demonstrating neuroprotective effects in oxidative stress models. The antioxidant activity contributes to hepatoprotective and anti-inflammatory effects.
[20, 23]Therapeutic Indications
Digestive System
Peptic ulcer disease and gastritis
One of the most extensively studied indications for licorice. DGL (deglycyrrhizinated licorice) has been evaluated in multiple clinical trials for gastric and duodenal ulcers. The mechanism involves stimulation of mucus secretion, enhancement of mucosal blood flow, promotion of epithelial cell proliferation, and cytoprotective prostaglandin effects. Carbenoxolone (a glycyrrhetinic acid derivative) was one of the first effective anti-ulcer drugs but was abandoned due to mineralocorticoid side effects, leading to development of DGL. Morgan et al. 1982 demonstrated DGL's efficacy comparable to cimetidine for gastric ulcer healing. Rees et al. 1979 confirmed duodenal ulcer healing with DGL. The GI-protective effect involves increased local prostaglandin synthesis and mucus production. DGL must be chewed or dissolved in the mouth before swallowing to mix with saliva, as the salivary epidermal growth factor is believed to contribute to mucosal healing.
[6, 7, 19]Functional dyspepsia
Licorice extracts improve dyspeptic symptoms including epigastric pain, heartburn, nausea, and belching. GutGard (a standardized licorice extract low in glycyrrhizin) was studied in a double-blind RCT by Raveendra et al. 2012 (n=50): significant improvement in symptom scores compared to placebo at 15 and 30 days. The spasmolytic and anti-inflammatory properties of licorice flavonoids contribute to symptom relief. DGL formulations are also used for functional dyspepsia.
[11, 19]Aphthous ulcers (canker sores)
DGL applied topically as a mouth rinse or dissolved patch has shown efficacy for aphthous ulcer healing and pain relief. Das et al. 1989 studied DGL mouthwash and found accelerated healing and reduced pain. The demulcent, anti-inflammatory, and mucosal-protective actions contribute to this effect. A practical approach is to dissolve DGL tablets in warm water and use as a mouthwash. Also effective as chewable DGL tablets held against the ulcer.
[13, 19]Gastroesophageal reflux disease (GERD)
DGL is widely recommended in naturopathic and integrative practice for GERD symptom management. The demulcent, mucosal-protective action provides symptomatic relief and may help protect esophageal mucosa from acid damage. Limited controlled clinical trial data specifically for GERD, but the mechanism of action and clinical experience support its use. Often recommended as part of a comprehensive approach including dietary and lifestyle modifications.
[19]Respiratory System
Upper respiratory catarrh and cough
Commission E approved indication. Licorice is one of the most widely used herbs globally for cough and upper respiratory complaints. The saponin content (glycyrrhizin) acts as an expectorant by stimulating bronchial mucus secretion and reducing mucus viscosity. The demulcent action soothes irritated mucous membranes. The anti-inflammatory and antispasmodic actions reduce bronchial inflammation and spasm. Used for both productive coughs (facilitating expectoration) and dry, irritating coughs (soothing the throat). Found in traditional cough remedies across TCM, Ayurveda, Unani, and European traditions.
[1, 2, 19]Sore throat and pharyngitis
Licorice gargle or lozenges provide symptomatic relief for sore throat. Agarwal et al. 2009 RCT found that licorice gargle significantly reduced postoperative sore throat incidence and severity compared to water gargle in intubated surgical patients. The demulcent and anti-inflammatory actions soothe inflamed pharyngeal mucosa. Widely used in traditional throat lozenges and cough drops.
[2, 12]Bronchitis and bronchial asthma (adjunctive)
Traditional use in TCM and Ayurveda for bronchitis and asthma. The antispasmodic action (bronchial smooth muscle relaxation via flavonoids) combined with expectorant and anti-inflammatory actions provides a rational basis for this use. In TCM, licorice is a component of many classical formulas for respiratory conditions including Ma Huang Tang and Xiao Qing Long Tang. Clinical evidence specifically for bronchitis and asthma is limited to traditional use and small uncontrolled studies.
[18, 19]Endocrine System
Adrenal insufficiency support (mild / HPA axis dysfunction)
Licorice supports adrenal function by inhibiting 11-beta-HSD2, thereby prolonging the half-life of endogenous cortisol and reducing the demand on the adrenal cortex for cortisol production. This mechanism is particularly relevant in patients with mild adrenal insufficiency, adrenal fatigue (a clinical concept used in integrative medicine), or chronic stress-related HPA axis dysfunction. Al-Dujaili et al. 2011 demonstrated that licorice consumption altered salivary cortisol:cortisone ratios consistent with 11-beta-HSD2 inhibition. This is NOT a treatment for primary adrenal insufficiency (Addison's disease), which requires corticosteroid replacement. The cortisol-sparing action must be monitored carefully to avoid mineralocorticoid excess. Duration of use is typically limited to 4-6 weeks at therapeutic doses of whole licorice.
[16, 19]Addison's disease (adjunctive — historical and integrative use only)
Historical use of licorice as an adjunct in Addison's disease was described before the availability of synthetic corticosteroids. Borst et al. 1953 and others documented that licorice could reduce the dose of cortisone required in Addisonian patients. This use is now primarily of historical interest, as synthetic corticosteroids are the standard of care. Some integrative practitioners use small doses of licorice as an adjunct to conventional therapy, but this must be done under close medical supervision with electrolyte monitoring.
[19, 20]Hepatobiliary System
Chronic hepatitis (B and C)
Glycyrrhizin has been studied extensively for chronic hepatitis in Japan and China. Stronger Neo-Minophagen C (SNMC), an intravenous glycyrrhizin preparation, has been used in Japan since the 1970s for chronic hepatitis C. Van Rossum et al. 1998 European multicenter trial confirmed SNMC reduced ALT levels in chronic hepatitis C patients. Kumada 2002 long-term study in Japan demonstrated that SNMC reduced progression to hepatocellular carcinoma in chronic hepatitis C patients over 10+ years of treatment. Oral glycyrrhizin preparations are also used, though bioavailability is lower. The mechanism involves anti-inflammatory, immunomodulatory, and direct antiviral effects. In the post-DAA (direct-acting antiviral) era for hepatitis C, the role of glycyrrhizin has diminished but remains relevant in resource-limited settings and for hepatoprotection in other liver diseases.
[8, 9, 21]Drug-induced liver injury and general hepatoprotection
Animal studies demonstrate hepatoprotective effects of glycyrrhizin against various hepatotoxins including carbon tetrachloride, acetaminophen, and aflatoxin. The mechanism involves membrane stabilization, antioxidant activity, and modulation of hepatic inflammatory cascades. Clinical evidence for drug-induced liver injury is limited to case series and small trials, primarily from Japan and China.
[20, 21]Immune System
Immune modulation and viral infections (adjunctive)
Glycyrrhizin demonstrates broad-spectrum antiviral activity in vitro against multiple enveloped viruses. Cinatl et al. 2003 demonstrated that glycyrrhizin inhibited SARS-CoV replication in vitro with an EC50 of approximately 300 mcg/mL, acting at multiple stages of the viral replication cycle. Activity has also been demonstrated against hepatitis C, HIV, herpes simplex, influenza A, and respiratory syncytial virus. The immunomodulatory effects (enhanced interferon-gamma production, NK cell activation, Th1/Th2 modulation) contribute to antiviral defense. Clinical translation of antiviral effects beyond hepatitis remains limited. Licorice is traditionally used in TCM immune-supporting formulas.
[10, 20, 21]Energetics
Temperature
neutral to cool (moistening)
Moisture
moist
Taste
Tissue States
dry/atrophy, hot/excitation, wind/tension
Licorice's energetics are complex and vary somewhat across traditions. In TCM, Gan Cao is classified as sweet (gan) in flavor, neutral to slightly warm in temperature, entering the heart, lung, spleen, and stomach channels. It is the quintessential 'harmonizer' -- used to moderate the actions of other herbs, reduce toxicity, alleviate pain, and improve the flavor of formulas. Raw Gan Cao (Sheng Gan Cao) is considered slightly cool and is used to clear heat and resolve toxicity; honey-fried Gan Cao (Zhi Gan Cao) is warmer and tonifies the qi and spleen more strongly. In Ayurveda, Yashtimadhu is sweet (madhura rasa) with a sweet post-digestive effect (madhura vipaka) and cooling potency (shita virya). It pacifies vata and pitta while potentially increasing kapha due to its sweet, heavy, unctuous qualities. In Western energetics, licorice is considered neutral to cool, moist, and sweet -- indicated for dry, atrophied, and irritated tissue states. Its moistening, demulcent quality makes it appropriate for dry coughs, dry or inflamed GI membranes, and conditions of tissue desiccation. The sweetness is not just organoleptic but reflects a genuine tissue-nourishing, building quality.
Traditional Uses
Traditional Chinese Medicine (TCM)
- Gan Cao ('sweet herb') -- one of the most frequently used herbs in the Chinese materia medica, appearing in an estimated 60-70% of all classical formulas
- Known as 'the great harmonizer' (guo lao) -- moderates the actions of other herbs in a formula, reduces toxicity of harsh ingredients, and harmonizes the overall effect
- Raw licorice (Sheng Gan Cao): Clears heat and resolves toxicity (sore throat, carbuncles, toxic swellings), moistens the lung to stop cough, relieves spasmodic pain
- Honey-fried licorice (Zhi Gan Cao): Tonifies the spleen and augments qi, nourishes the heart qi and blood (Zhi Gan Cao Tang for irregular pulse/palpitations)
- Antidote for toxic herbs and drugs -- traditionally added to formulas containing aconite (fu zi) or other potentially toxic ingredients to moderate their toxicity
- Component of Si Jun Zi Tang (Four Gentlemen Decoction) for qi deficiency, and innumerable other classical formulas
"First recorded in the Shen Nong Ben Cao Jing (Divine Husbandman's Classic of the Materia Medica, c. 200 CE) as a superior-class herb, meaning it could be taken long-term without harm (at traditional doses). Classified as sweet in flavor, neutral in temperature, entering 12 channels (all channels). The statement that Gan Cao 'enters all 12 channels' is unique in the materia medica and reflects its extraordinary breadth of use. Zhang Zhongjing (c. 200 CE) used Gan Cao in over 70 formulas in the Shang Han Lun (Treatise on Cold Damage)."
[18]
Ayurveda
- Yashtimadhu (Sanskrit: 'sweet stick') -- one of the most important Ayurvedic herbs for respiratory and digestive conditions
- Pacifies vata and pitta doshas; may increase kapha due to sweet, heavy nature
- Used for dry cough, hoarseness, and sore throat (often with honey)
- Digestive complaints: gastritis, hyperacidity, peptic ulcer
- Adrenal tonic and rejuvenative (rasayana) -- supports ojas (vital essence)
- Eye wash preparations for inflammatory eye conditions
- Used externally as a paste for inflammatory skin conditions and wounds
- Component of many classical formulations including Sitopaladi Churna and Yashtimadhu Ghrita
"Described in the Charaka Samhita and Sushruta Samhita (c. 600-200 BCE). Classified as madhura (sweet) rasa, shita (cooling) virya, madhura vipaka. Considered a medhya rasayana (brain tonic). The name Yashtimadhu literally means 'sweet root/stick.' In the Ayurvedic classification of tastes, the predominant sweet taste makes it a nourishing, building herb rather than a reducing one, which is why it can aggravate kapha conditions."
European/Western Herbalism
- Cough remedy and expectorant -- one of the most widely used traditional cough herbs in European medicine
- Sore throat and pharyngitis (as lozenge, gargle, or tea)
- Stomach complaints: gastritis, peptic ulcer, heartburn
- Adrenal support and stress-related fatigue
- Anti-inflammatory for joint and muscle pain (less common use)
- Flavoring agent in herbal formulas to mask bitter or unpleasant tastes
- Mild laxative (through gentle stimulation and moistening of the bowel)
"Used medicinally in Europe since antiquity. Theophrastus (c. 300 BCE) described 'Scythian root' used by nomadic peoples of the Black Sea region for thirst and as a medicinal. Dioscorides (De Materia Medica, c. 70 CE) recommended it for stomach, chest, and liver complaints and for throat ulcers. The name 'glycyrrhiza' derives from Greek glykys (sweet) + rhiza (root). Widely used in medieval European medicine. Listed in virtually all major European pharmacopeias from the 16th century onward. The German Commission E approved licorice root for catarrh of the upper respiratory tract and gastric/duodenal ulcers. Eclectic physicians in 19th-century America used licorice as a demulcent, expectorant, and laxative, and as a vehicle to make other medicines palatable."
Ancient Egyptian and Mesopotamian
- One of the oldest documented medicinal plants in human history
- Found in the tomb of Tutankhamun (c. 1323 BCE) among other medicinal plants and provisions
- Documented in Assyrian cuneiform tablets and Egyptian papyri for respiratory and digestive complaints
- Used as a flavoring and medicinal agent throughout the ancient Near East
"Licorice root has been found in archaeological sites dating back thousands of years, including the tomb of the Egyptian pharaoh Tutankhamun. Assyrian tablets from the library of Ashurbanipal (c. 650 BCE) mention licorice for medicinal purposes. The long history of licorice use across virtually all major civilizations of the Old World (Egyptian, Mesopotamian, Greek, Roman, Chinese, Indian, Arabic) makes it one of the most widely and continuously used medicinal plants in human history."
[21]
Unani (Greco-Islamic) medicine
- Known as 'Sus' or 'Asl-us-Sus' in Arabic/Unani
- Used for cough, sore throat, hoarseness
- Stomach and liver complaints
- Thirst-quenching (a traditional use dating to Scythian and Bedouin peoples)
- Kidney and bladder disorders
"Extensively described in Unani medical texts following the Greek tradition. Avicenna (Ibn Sina) in the Canon of Medicine described licorice for chest and lung complaints, sore throat, and kidney conditions. Classified as temperate to slightly warm, moist in the second degree in Unani humoral theory. The Unani tradition shares the Greek understanding of licorice's demulcent and pectoral properties."
[2]
Modern Research
DGL (deglycyrrhizinated licorice) for peptic ulcer disease
Multiple clinical trials from the 1970s-1980s evaluated DGL for gastric and duodenal ulcers, building on the success but safety concerns of carbenoxolone (a glycyrrhetinic acid derivative used in the 1960s-70s as an anti-ulcer drug).
Findings: Morgan et al. 1982 RCT compared DGL (760 mg tid) with cimetidine (200 mg tid + 400 mg at night) in 100 patients with gastric ulcer. Both groups showed similar ulcer healing rates at 6 and 12 weeks, with no significant difference between groups. Rees et al. 1979 reported that DGL (380 mg tid) promoted duodenal ulcer healing. The mechanism involves stimulation of gastric mucus secretion (quality and quantity), enhancement of mucosal prostaglandin synthesis, promotion of epithelial cell proliferation, and improvement of mucosal blood flow. DGL avoids the mineralocorticoid side effects of whole licorice/carbenoxolone by removing glycyrrhizin to below 3%.
Limitations: Most DGL ulcer trials date from the 1970s-1980s and predate modern trial design standards and the understanding of H. pylori's role in ulcer disease. Many had small sample sizes and variable methodological quality. DGL has not been studied in comparison with proton pump inhibitors (PPIs). In the modern era of PPI-based ulcer treatment and H. pylori eradication, DGL is positioned as a complementary or alternative approach rather than a primary treatment.
Glycyrrhizin for chronic hepatitis C (SNMC/intravenous glycyrrhizin)
Stronger Neo-Minophagen C (SNMC), an intravenous glycyrrhizin preparation, has been used in Japan since the 1970s for chronic hepatitis treatment. Several clinical trials and long-term observational studies have evaluated its efficacy.
Findings: Van Rossum et al. 1998 randomized European multicenter trial (n=57) evaluated SNMC in chronic hepatitis C. IV glycyrrhizin (240 mg, 3x/week for 4 weeks) significantly reduced ALT levels compared to placebo (P<0.002). ALT returned to elevated levels after cessation, suggesting the effect requires ongoing treatment. Kumada 2002 long-term retrospective study of 453 patients treated with SNMC for chronic hepatitis C over 2-16 years found a significantly lower rate of hepatocellular carcinoma development (2.5% vs 16% in historical controls at 10 years). SNMC's mechanism involves anti-inflammatory, immunomodulatory, and cytoprotective effects on hepatocytes.
Limitations: Van Rossum et al. study was small and short-term. ALT reduction was not sustained after treatment cessation. The Kumada study was retrospective and non-randomized. In the DAA era, hepatitis C is now curable in >95% of cases, substantially reducing the clinical relevance of glycyrrhizin for this indication. Intravenous delivery limits practical application compared to oral formulations.
Glycyrrhizin antiviral activity against SARS-CoV
In vitro study evaluating glycyrrhizin and other antiviral compounds against the SARS-associated coronavirus, published during the 2003 SARS outbreak.
Findings: Cinatl et al. 2003 tested glycyrrhizin against SARS-CoV replication in Vero cells. Glycyrrhizin inhibited viral replication with an EC50 of approximately 300 mcg/mL and a selectivity index >67. Glycyrrhizin was most effective when given both during and after viral adsorption, suggesting activity at multiple stages of the viral cycle. It was more effective than ribavirin, 6-azauridine, pyrazofurin, and mycophenolic acid in this model. Mechanism involved inhibition of viral adsorption and penetration, as well as possible stimulation of nitric oxide synthase in macrophages.
Limitations: In vitro study only; concentrations achieving antiviral activity (300 mcg/mL) may not be achievable systemically with oral dosing at safe levels. No clinical trials of glycyrrhizin for SARS-CoV were conducted. The relevance to SARS-CoV-2 (COVID-19) is speculative, though it spurred further research. The gap between in vitro effective concentrations and achievable safe plasma levels is a significant translational challenge.
[10]
Glabridin as phytoestrogen and skin-lightening agent
Research on glabridin, the principal isoflavane of G. glabra, for estrogenic activity and dermatological applications.
Findings: Glabridin demonstrates selective estrogen receptor modulator (SERM)-like activity, binding to both ER-alpha and ER-beta with moderate affinity. It exhibits estrogen-like effects on bone (stimulating osteoblast activity) while showing anti-proliferative effects on breast cancer cell lines in some studies. Tamir et al. 2000 characterized its estrogenic binding properties. Glabridin also potently inhibits tyrosinase (the rate-limiting enzyme in melanin synthesis), making it effective as a skin-lightening/depigmenting agent. Clinical studies in cosmetic dermatology have confirmed skin-lightening effects of topical licorice extracts standardized to glabridin. Additionally, glabridin demonstrates anti-inflammatory (inhibits superoxide production and COX activity), neuroprotective, and anti-atherogenic (inhibits LDL oxidation) effects.
Limitations: Most estrogenic activity data is from in vitro studies. Clinical relevance of phytoestrogenic effects at typical oral licorice doses is uncertain. Glabridin has poor oral bioavailability due to extensive first-pass metabolism. Species-specific: glabridin is found primarily in G. glabra, not in G. uralensis (the TCM species), limiting the applicability of these findings to Chinese licorice.
Licorice flavonoid oil (LFO) for body fat reduction
Clinical evaluation of licorice flavonoid oil, a flavonoid-rich extract of licorice, for effects on body weight and fat composition.
Findings: Tominaga et al. 2006 double-blind RCT (n=103 overweight subjects) evaluated licorice flavonoid oil (300 mg and 600 mg daily for 8 weeks). The 900 mg group showed significant reductions in body weight, BMI, body fat mass, and LDL cholesterol compared to placebo. The mechanism may involve activation of PPAR-alpha and inhibition of 11-beta-HSD1 in adipose tissue, affecting local cortisol metabolism and adipogenesis.
Limitations: Single study with modest effect sizes. Industry-funded. Long-term safety and efficacy not established. LFO is a specific extract with a defined composition; results may not generalize to whole licorice root preparations.
[15]
Standardized licorice extract (GutGard) for functional dyspepsia
Double-blind, randomized, placebo-controlled trial evaluating GutGard, a standardized licorice root extract with reduced glycyrrhizin, for functional dyspepsia.
Findings: Raveendra et al. 2012 RCT (n=50 patients with functional dyspepsia) evaluated GutGard (75 mg twice daily) vs placebo for 30 days. GutGard significantly reduced overall symptom scores (P<0.05 at day 15 and P<0.001 at day 30). Individual symptoms including nausea, epigastric fullness, epigastric pain, and belching were all significantly improved. No adverse effects on serum electrolytes, liver function, or kidney function were observed.
Limitations: Small sample size (n=50). Single-center study. Short treatment duration (30 days). Industry-funded. GutGard is a specific commercial extract; results may not be directly applicable to other licorice preparations.
[11]
Licorice gargle for prevention of postoperative sore throat
Randomized, double-blind trial evaluating licorice gargle for prevention of sore throat following endotracheal intubation for surgery.
Findings: Agarwal et al. 2009 RCT (n=40 adult surgical patients) randomized patients to gargle with licorice water (0.5 g licorice in 30 mL water) or plain water 5 minutes before induction of anesthesia. Incidence of postoperative sore throat was significantly lower in the licorice group (30% vs 70%, P=0.02) at all measured time points (0, 2, 4, and 24 hours). Severity scores were also significantly lower in the licorice group.
Limitations: Small sample size. Single-center study. Only evaluated one dose/preparation. The mechanism (likely local anti-inflammatory and demulcent effects on the pharyngeal mucosa) is plausible but was not specifically investigated.
[12]
Preparations & Dosage
Decoction
Strength: 2-6 g dried root per 360-480 mL water
Simmer 2-6 g of dried, sliced licorice root in 360-480 mL of water for 15-20 minutes. Strain and drink. In TCM practice, licorice is typically added to multi-herb decoctions at the standard dosage and simmered for the full decoction time. May be simmered longer (30-45 minutes) for a stronger preparation.
180-240 mL (6-8 oz), 2-3 times daily
2-3 times daily
Maximum 4-6 weeks of continuous use at therapeutic doses unless using DGL. Shorter courses preferred. May be used intermittently for longer periods.
Children over 4 years: half adult dose under practitioner supervision. Not recommended for prolonged use in children.
Standard TCM dosage for Gan Cao is 2-10 g per day in decoction (varies by indication and formula context). Decoction is the primary preparation method in TCM. The sweet taste makes licorice one of the few herbs that is pleasant to take as a simple decoction. In formulas, licorice often serves a dual role: therapeutic agent and flavor harmonizer. IMPORTANT: Duration limit applies to whole licorice preparations due to glycyrrhizin content; DGL preparations do not have this restriction.
Infusion (Tea)
Strength: 2-4 g dried root per 240 mL water
Steep 1-2 teaspoons (approximately 2-4 g) of dried, sliced or cut licorice root in 240 mL (8 oz) of just-boiled water for 10-15 minutes, covered. Strain and drink. A longer steep (20-30 minutes) extracts more glycyrrhizin and produces a sweeter tea.
1-2 cups (240-480 mL) up to 3 times daily
2-3 times daily for respiratory complaints; as needed for sore throat
Maximum 4-6 weeks continuous use (whole licorice). Short-term use preferred.
Children over 4: half adult dose for short-term use only (up to 1 week). Consult practitioner.
Pleasant-tasting preparation suitable for self-care use. Commonly used for sore throat, cough, and digestive discomfort. May be combined with other herbs (e.g., marshmallow root for enhanced demulcent effect, ginger for respiratory infections, peppermint for digestive complaints). Licorice tea is naturally sweet and rarely requires additional sweetening.
Tincture
Strength: 1:5, 40-60% ethanol
Macerate dried licorice root in 40-60% ethanol at a ratio of 1:5 for 2-4 weeks. Shake daily. Press and filter. Some practitioners prefer a higher alcohol percentage (60%) for optimal glycyrrhizin extraction.
2-5 mL, 3 times daily
3 times daily
Maximum 4-6 weeks continuous use. Shorter courses preferred.
Not established for tincture form. Glycerite (glycerin-based) preparations may be preferred for children.
Tincture provides a concentrated liquid form convenient for dosing. Often included in multi-herb tincture formulas at 10-20% of the total formula as a harmonizer and flavor improver. The sweet taste of licorice tincture can mask bitter flavors of other herbs in combination formulas. Calculate glycyrrhizin intake from all sources when using licorice tincture to ensure total daily glycyrrhizin does not exceed safe thresholds.
[19]
DGL-chewable-tablet
Strength: 380 mg DGL per tablet (glycyrrhizin content <3% by weight)
DGL (deglycyrrhizinated licorice) tablets must be CHEWED thoroughly (not swallowed whole) 15-20 minutes before meals. Chewing is considered important as it mixes the DGL with salivary epidermal growth factor (EGF), which is believed to enhance mucosal healing. Alternatively, tablets may be dissolved in warm water and taken as a drink or used as a mouthwash.
380-760 mg (1-2 tablets), chewed 15-20 minutes before meals, 3 times daily. For aphthous ulcers: dissolve 200 mg DGL in 200 mL warm water and use as a mouthwash, 4 times daily.
3 times daily before meals for GI complaints; 4 times daily as mouthwash for oral ulcers
8-16 weeks for ulcer healing. May be used long-term for maintenance. No duration limit for DGL (unlike whole licorice) as glycyrrhizin content is below 3%.
Children over 6: 1 tablet (380 mg) chewed before meals under practitioner supervision
DGL is the preferred form for gastrointestinal indications (peptic ulcer, gastritis, GERD) because it provides the mucosal-protective benefits of licorice flavonoids and other non-saponin constituents without the mineralocorticoid risks of glycyrrhizin. The chewing requirement is based on the Morgan et al. 1982 protocol, which emphasized mixing with saliva. Some newer DGL products do not require chewing (powder or liquid forms). DGL does NOT provide the adrenal-supportive, antiviral, or hepatoprotective effects that require glycyrrhizin. Patients seeking GI benefits should use DGL; patients seeking adrenal or immune support need whole licorice with appropriate monitoring.
powdered-root
Strength: Whole powdered dried root, typically 4-6% glycyrrhizin content
Finely powdered dried licorice root taken in capsules, mixed with honey, or added to herbal formula powders.
1-4 g powdered root daily in divided doses
2-3 times daily
Maximum 4-6 weeks continuous use at therapeutic doses
Not established. Consult practitioner.
Powdered root in capsules is a simple and effective way to take licorice. Also used in Ayurvedic churna (powder) preparations, often mixed with honey (a traditional Ayurvedic anupana/vehicle for Yashtimadhu). Honey-fried licorice powder (Zhi Gan Cao) is a specific TCM processed form with enhanced qi-tonifying properties. Ensure glycyrrhizin content is known for safety monitoring.
Standardized Extract
Strength: Variable. Products may be standardized to glycyrrhizin content (e.g., 10-25%), glabridin content, or total flavonoids.
Commercially prepared standardized extracts with defined levels of glycyrrhizin, glabridin, or other marker compounds. Follow manufacturer's dosing instructions based on standardization.
Product-specific. GutGard: 75 mg twice daily. Other standardized products: 250-500 mg daily depending on glycyrrhizin content. Calculate glycyrrhizin intake to stay below 100 mg/day.
1-3 times daily depending on product
Follow product-specific guidelines. Duration limits apply based on glycyrrhizin content.
Not established for most standardized products
Standardized extracts allow more precise dosing of active compounds. Some products are specifically formulated with reduced glycyrrhizin (like GutGard) for safer long-term use. Others are standardized to higher glycyrrhizin content for hepatoprotective or immune-supporting applications. Always verify the glycyrrhizin content per dose when using standardized extracts.
topical
Strength: 1-2% glycyrrhetinic acid cream; DGL mouthwash as above
For skin: apply licorice extract cream or gel containing glabridin or glycyrrhetinic acid to affected area. For mouth/throat: dissolve DGL in warm water as a mouthwash, or gargle with licorice decoction.
Topical: apply 1-2% glycyrrhetinic acid cream 2-3 times daily. Mouthwash: dissolve 200 mg DGL in 200 mL warm water, swish for 2-3 minutes, 4 times daily. Gargle: 0.5 g licorice in 30 mL water, gargle 1-2 minutes.
2-4 times daily depending on indication
Until symptom resolution. No systemic absorption concerns with topical use at standard concentrations.
Topical: under practitioner guidance. Mouthwash: children over 6 who can reliably spit (not swallow).
Topical licorice preparations avoid systemic glycyrrhizin effects. Glycyrrhetinic acid creams have been studied for eczema and atopic dermatitis with positive results. Glabridin-containing preparations are used in cosmetic dermatology for skin lightening and depigmentation. Licorice mouthwash for aphthous ulcers is a well-tolerated, practical intervention.
Safety & Interactions
Class 2b
Not to be used during lactation (AHPA Botanical Safety Handbook)
Contraindications
Glycyrrhizin inhibits 11-beta-HSD2, causing cortisol to activate mineralocorticoid receptors, leading to sodium retention, potassium excretion, and water retention. This directly raises blood pressure. Patients with existing hypertension are at significantly increased risk of hypertensive crisis with whole licorice products. DGL (with glycyrrhizin removed) does not carry this risk and may be used by hypertensive patients.
The sodium and water retention caused by glycyrrhizin can worsen fluid overload in heart failure patients. Hypokalemia from glycyrrhizin can also predispose to cardiac arrhythmias, particularly dangerous in patients with underlying cardiac disease. Multiple case reports document hospitalizations for licorice-induced hypokalemia with cardiac complications.
Impaired renal function reduces the body's ability to compensate for glycyrrhizin-induced electrolyte disturbances. Patients with kidney disease are at increased risk of hypokalemia and hypernatremia. Potassium wasting is exacerbated when renal compensatory mechanisms are compromised.
Patients with cirrhosis have altered aldosterone metabolism (reduced hepatic clearance) which potentiates the mineralocorticoid effects of glycyrrhizin. Paradoxically, while glycyrrhizin has hepatoprotective effects in chronic hepatitis, its use in cirrhosis is contraindicated due to the risk of severe fluid retention, ascites worsening, and electrolyte imbalance. Cirrhotic patients already prone to ascites and hyponatremia are particularly vulnerable.
Glycyrrhizin directly promotes renal potassium excretion through mineralocorticoid receptor activation. Pre-existing hypokalemia can be dangerously worsened. This includes patients on potassium-depleting medications (thiazide and loop diuretics, corticosteroids, laxatives). Severe hypokalemia can cause muscle weakness, rhabdomyolysis, cardiac arrhythmias, and potentially cardiac arrest.
The phytoestrogenic components of licorice (glabridin, isoflavonoids) have theoretical potential to worsen estrogen-sensitive conditions. This is a precautionary contraindication based on the SERM-like activity of licorice flavonoids rather than documented clinical events. Applies primarily to G. glabra (which contains glabridin) rather than G. uralensis.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| Thiazide and loop diuretics (hydrochlorothiazide, furosemide, bumetanide) (Diuretics (potassium-depleting)) | major | Additive potassium depletion. Both licorice (via mineralocorticoid effect) and potassium-depleting diuretics promote renal potassium excretion. Combined use significantly increases the risk of hypokalemia and its complications (muscle weakness, arrhythmias, cardiac arrest). |
| Corticosteroids (prednisone, prednisolone, dexamethasone, hydrocortisone) (Corticosteroids) | major | Glycyrrhizin inhibits 11-beta-HSD2, reducing the conversion of active cortisol to inactive cortisone in the kidney. This potentiates the effects of both endogenous and exogenous corticosteroids, potentially increasing their mineralocorticoid side effects (sodium retention, potassium loss, hypertension) and prolonging their duration of action. The interaction is synergistic for fluid retention and hypokalemia. |
| Digoxin (Lanoxin) (Cardiac glycosides) | major | Licorice-induced hypokalemia increases sensitivity to digoxin toxicity. Hypokalemia enhances digoxin binding to Na+/K+-ATPase, increasing the risk of digoxin-induced cardiac arrhythmias even at therapeutic serum digoxin levels. This is a well-established pharmacological interaction. |
| Antihypertensive agents (all classes) (Antihypertensive agents) | moderate | Licorice-induced sodium retention and volume expansion can counteract the blood-pressure-lowering effects of antihypertensive medications, leading to treatment failure or the need for dose escalation. |
| Warfarin and other anticoagulants (Anticoagulants) | moderate | Glycyrrhizin may inhibit platelet aggregation (in vitro). Hypokalemia from chronic licorice use can affect cardiac rhythm, complicating anticoagulant management. Some evidence suggests licorice may affect CYP3A4 metabolism, potentially altering warfarin levels, though clinical significance is unclear. |
| Stimulant and osmotic laxatives (Laxatives) | moderate | Chronic laxative use can cause potassium depletion via GI losses. Combined with licorice-induced renal potassium losses, the risk of hypokalemia is amplified. |
| Oral contraceptives and hormone replacement therapy (HRT) (Hormonal therapies) | theoretical | Estrogen-containing preparations may enhance the mineralocorticoid effects of glycyrrhizin by increasing cortisol-binding globulin levels and potentially affecting 11-beta-HSD2 activity. Licorice's phytoestrogenic components could theoretically add to estrogenic load. |
| MAO inhibitors and serotonergic drugs (Antidepressants) | theoretical | Liquiritin (a licorice flavonoid glycoside) has demonstrated serotonergic activity in animal models. Theoretical concern for serotonergic potentiation, though not documented clinically at standard licorice doses. |
Pregnancy & Lactation
Pregnancy
avoid
Lactation
insufficient data
Pregnancy: Licorice should be AVOIDED during pregnancy. Strandberg et al. 2001 Finnish cohort study found that heavy licorice consumption during pregnancy (>500 mg glycyrrhizin/week) was associated with significantly shorter gestational duration. Strandberg et al. 2002 follow-up found that heavy maternal licorice exposure was associated with higher salivary cortisol levels and behavioral problems in exposed children at age 8. The mechanism involves glycyrrhizin's inhibition of placental 11-beta-HSD2, which normally protects the fetus from maternal cortisol. Loss of this placental cortisol barrier may affect fetal HPA axis development. The WHO and most pharmacopeias contraindicate licorice during pregnancy or recommend avoidance. Small amounts in food are probably not harmful, but medicinal doses should be avoided. DGL is likely safer during pregnancy as it lacks glycyrrhizin, but data is insufficient. Lactation: Insufficient safety data for licorice use during lactation. The potential for glycyrrhizin to affect infant electrolyte balance through breast milk is unknown. Conservative approach: avoid whole licorice during breastfeeding; DGL is likely acceptable but consult a qualified practitioner.
Adverse Effects
References
Monograph Sources
- [1] German Commission E (Bundesinstitut fur Arzneimittel und Medizinprodukte). Commission E Monograph: Liquiritiae radix (Licorice Root) -- Positive. Bundesanzeiger (Federal Gazette) (1998)
- [2] World Health Organization. WHO Monographs on Selected Medicinal Plants, Volume 1: Radix Glycyrrhizae. World Health Organization, Geneva (1999) : 183-194
- [3] European Scientific Cooperative on Phytotherapy (ESCOP). ESCOP Monographs: Liquiritiae radix -- Licorice Root. ESCOP Monographs, 2nd edition. Thieme, Stuttgart (2003)
- [4] National Center for Complementary and Integrative Health (NCCIH). Licorice Root. NCCIH, National Institutes of Health (2020)
- [5] Committee on Herbal Medicinal Products (HMPC), European Medicines Agency. Assessment report on Glycyrrhiza glabra L. and/or Glycyrrhiza inflata Bat. and/or Glycyrrhiza uralensis Fisch., radix. European Medicines Agency (2012)
Clinical Studies
- [6] Morgan AG, McAdam WA, Pacsoo C, Darnborough A. Comparison between cimetidine and Caved-S in the treatment of gastric ulceration, and subsequent maintenance therapy. Gut (1982) ; 23 : 545-551 . DOI: 10.1136/gut.23.6.545 . PMID: 6806155
- [7] Rees WD, Rhodes J, Wright JE, Stamford LF, Bennett A. Effect of deglycyrrhizinated liquorice on gastric mucosal damage by aspirin. Scand J Gastroenterol (1979) ; 14 : 605-607 . DOI: 10.3109/00365527909181942 . PMID: 531498
- [8] van Rossum TG, Vulto AG, de Man RA, Brouwer JT, Schalm SW. Review of the evidence for glycyrrhizin as a new therapy for chronic hepatitis C. Am J Gastroenterol (1998) ; 93 : 2327-2332 . DOI: 10.1111/j.1572-0241.1998.00600.x . PMID: 9860390
- [9] Kumada H. Long-term treatment of chronic hepatitis C with glycyrrhizin [stronger neo-minophagen C (SNMC)] for preventing liver cirrhosis and hepatocellular carcinoma. Oncology (2002) ; 62 Suppl 1 : 94-100 . DOI: 10.1159/000048283 . PMID: 11868791
- [10] Cinatl J, Morgenstern B, Bauer G, Chandra P, Rabenau H, Doerr HW. Glycyrrhizin, an active component of liquorice roots, and replication of SARS-associated coronavirus. Lancet (2003) ; 361 : 2045-2046 . DOI: 10.1016/S0140-6736(03)13615-X . PMID: 12814717
- [11] Raveendra KR, Jayachandra, Srinivasa V, Sushma KR, Allan JJ, Goudar KS, Shivaprasad HN, Venkateshwarlu K, Geetharani P, Sushma G, Agarwal A. An extract of Glycyrrhiza glabra (GutGard) alleviates symptoms of functional dyspepsia: a randomized, double-blind, placebo-controlled study. Evid Based Complement Alternat Med (2012) ; 2012 : 216970 . DOI: 10.1155/2012/216970 . PMID: 22536282
- [12] Agarwal A, Gupta D, Agarwal S, Owesi R, Sayed H. An evaluation of the efficacy of licorice gargle for attenuating postoperative sore throat: a prospective, randomized, single-blind study. Anesth Analg (2009) ; 109 : 77-81 . DOI: 10.1213/ane.0b013e3181a6ad47 . PMID: 19535696
- [13] Das SK, Das V, Gulati AK, Singh VP. Deglycyrrhizinated liquorice in aphthous ulcers. J Assoc Physicians India (1989) ; 37 : 647 . PMID: 2632490
- [14] Omar HR, Komarova I, El-Ghonemi M, Fathy A, Rashad R, Abdelmalak HD, Yerber MR, Ali Y, Helal E, Camporesi EM. Licorice abuse: time to send a warning message. Ther Adv Endocrinol Metab (2012) ; 3 : 125-138 . DOI: 10.1177/2042018812454322 . PMID: 23185686
- [15] Tominaga Y, Nakagawa K, Mae T, Kitano M, Yokota S, Arai T, Ikematsu H, Inoue S. Licorice flavonoid oil reduces total body fat and visceral fat in overweight subjects: a randomized, double-blind, placebo-controlled study. Obes Res Clin Pract (2006) ; 3 : 169-178 . DOI: 10.1016/j.orcp.2009.04.005
- [16] Al-Dujaili EA, Kenyon CJ, Nicol MR, Mason JI. Liquorice and glycyrrhetinic acid increase DHEA and deoxycorticosterone levels in vivo and in vitro by inhibiting adrenal SULT2A1 activity. Mol Cell Endocrinol (2011) ; 336 : 102-109 . DOI: 10.1016/j.mce.2010.12.011 . PMID: 21184804
- [17] Strandberg TE, Jarvenpaa AL, Vanhanen H, McKeigue PM. Birth outcome in relation to licorice consumption during pregnancy. Am J Epidemiol (2001) ; 153 : 1085-1088 . DOI: 10.1093/aje/153.11.1085 . PMID: 11390327
Traditional Texts
- [18] Bensky D, Clavey S, Stoger E. Chinese Herbal Medicine: Materia Medica (3rd edition). Eastland Press, Seattle (2004)
- [19] Bone K, Mills S. Principles and Practice of Phytotherapy: Modern Herbal Medicine (2nd edition). Churchill Livingstone/Elsevier (2013)
Pharmacopeias & Reviews
- [20] Asl MN, Hosseinzadeh H. Review of pharmacological effects of Glycyrrhiza sp. and its bioactive compounds. Phytother Res (2008) ; 22 : 709-724 . DOI: 10.1002/ptr.2362 . PMID: 18446848
- [21] Fiore C, Eisenhut M, Krausse R, Raber E, Mader A, Grubinger M, Mayer P, Kloft C, Rabenau H, Doerr HW. Antiviral effects of Glycyrrhiza species. Phytother Res (2008) ; 22 : 141-148 . DOI: 10.1002/ptr.2295 . PMID: 17886224
- [22] Isbrucker RA, Burdock GA. Risk and safety assessment on the consumption of Licorice root (Glycyrrhiza sp.), its extract and powder as a food ingredient, with emphasis on the pharmacology and toxicology of glycyrrhizin. Regul Toxicol Pharmacol (2006) ; 46 : 167-192 . DOI: 10.1016/j.yrtph.2006.06.002 . PMID: 16884839
- [23] Pastorino G, Cornara L, Soares S, Rodrigues F, Oliveira MB. Liquorice (Glycyrrhiza glabra): A phytochemical and pharmacological review. Phytother Res (2018) ; 32 : 2323-2339 . DOI: 10.1002/ptr.6178 . PMID: 30117204
- [24] Tamir S, Eizenberg M, Somjen D, Stern N, Shelach R, Kaye A, Vaya J. Estrogenic and antiproliferative properties of glabridin from licorice in human breast cancer cells. Cancer Res (2000) ; 60 : 5704-5709 . PMID: 11059763
Last updated: 2026-02-26 | Status: review