Licorice Root

• Anti-inflammatory
• Adrenal support
• Mucosal protection
• Antioxidant protection

• Digestive health
• Respiratory support
• Liver protection
• Immune modulation
• Skin health
• Oral health
• Hormonal balance

Licorice root (Glycyrrhiza glabra) exerts its diverse therapeutic effects through a complex array of bioactive compounds, with glycyrrhizin (also called glycyrrhizic acid) being the most well-studied active constituent. Additional bioactive compounds include flavonoids (liquiritin, isoliquiritin, liquiritigenin), chalcones, coumarins, triterpenoids, and various polyphenols. The anti-inflammatory properties of licorice stem from multiple pathways. Glycyrrhizin and its metabolite glycyrrhetinic acid inhibit the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which normally converts active cortisol to inactive cortisone.

By inhibiting this enzyme, licorice effectively increases cortisol availability in tissues, enhancing its anti-inflammatory effects. Additionally, licorice flavonoids inhibit key inflammatory enzymes including cyclooxygenase (COX), lipoxygenase (LOX), and phospholipase A2, reducing the production of pro-inflammatory mediators. Licorice compounds also suppress nuclear factor-kappa B (NF-κB) activation, a master regulator of inflammatory responses, and inhibit the production of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6). The adrenal support function of licorice is primarily due to its cortisol-sparing effect through 11β-HSD2 inhibition, which helps maintain healthy cortisol levels during periods of stress.

This mechanism explains licorice’s traditional use as an adaptogen that helps the body respond to and recover from stress. For mucosal protection, particularly in the digestive tract, licorice contains mucilaginous compounds that form a protective coating on the gastric and intestinal mucosa, shielding it from irritants and acid. Glycyrrhizin and flavonoids also stimulate the production of mucin, a key component of the gastric mucosal barrier. Additionally, licorice compounds increase prostaglandin E2 production in the stomach, which enhances mucosal blood flow and stimulates mucus secretion.

The antioxidant activity of licorice involves direct free radical scavenging by its flavonoids and polyphenols, as well as enhancement of endogenous antioxidant defenses through upregulation of enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase. In the respiratory system, licorice acts as an expectorant by stimulating the production of respiratory tract secretions, making coughs more productive. Its demulcent properties soothe irritated respiratory mucosa, while its anti-inflammatory effects reduce bronchial inflammation. For liver protection, licorice compounds enhance detoxification pathways, particularly phase II conjugation reactions, and protect hepatocytes from oxidative damage.

Glycyrrhizin has demonstrated antiviral properties against hepatitis viruses, particularly hepatitis C, by inhibiting viral replication and reducing liver inflammation. The immune-modulating effects of licorice involve enhancement of macrophage activity, modulation of T-cell function, and regulation of cytokine production. Rather than simply stimulating the immune system, licorice appears to help normalize immune function, potentially beneficial in both immunodeficiency and autoimmune conditions. For skin health, licorice compounds inhibit tyrosinase enzyme activity, potentially reducing hyperpigmentation.

Its anti-inflammatory and antimicrobial properties help in conditions like eczema, psoriasis, and acne. Glabridin, a licorice isoflavone, has demonstrated significant skin-lightening effects. In oral health applications, licorice compounds inhibit the growth of cavity-causing bacteria like Streptococcus mutans and reduce the formation of dental plaque. For hormonal balance, particularly in women, licorice contains phytoestrogens that can bind to estrogen receptors with weak activity.

It also affects steroid hormone metabolism through its effects on various enzymes involved in hormone synthesis and breakdown. The antimicrobial properties of licorice stem from compounds like glycyrrhizin, glabridin, and licochalcone A, which have demonstrated activity against various bacteria, viruses, fungi, and parasites through mechanisms including disruption of microbial membranes and inhibition of microbial enzyme systems.

Whole licorice root (containing glycyrrhizin): 1-5 grams of dried root daily, divided into 2-3 doses, not to exceed 7 grams daily; or 250-500 mg standardized extract (containing 4-5% glycyrrhizin) 1-3 times daily. Deglycyrrhizinated licorice (DGL): 380-1140 mg, typically taken 15-20 minutes before meals for digestive issues, up to 3 times daily.

Variable; glycyrrhizin has poor oral bioavailability (approximately 3-4%) as it is not well absorbed in the small intestine. However, intestinal bacteria convert glycyrrhizin to glycyrrhetinic acid, which has better absorption (approximately 20-30%). Flavonoids and other polyphenols in licorice have moderate bioavailability, typically in the range of 10-30%, depending on the specific compound.

Combining with black pepper extract (piperine) can increase absorption by inhibiting P-glycoprotein efflux and certain metabolic enzymes, Taking with a fat-containing meal enhances absorption of fat-soluble compounds in licorice, Traditional preparation with honey or ghee (clarified butter) in Ayurvedic medicine may enhance absorption and palatability, Liposomal formulations can significantly improve bioavailability by enhancing solubility and cellular uptake, Fermented preparations may enhance bioavailability through partial breakdown of glycosides by microbial enzymes, Chewing DGL tablets thoroughly allows compounds to mix with saliva, enhancing their protective effect on the gastric mucosa, Alcohol-based extracts (tinctures) may provide better extraction and absorption of certain compounds compared to water-based preparations, Standardized extracts with higher active compound content generally provide better bioavailability than raw herb powder

For digestive issues, DGL should be taken 15-20 minutes before meals to allow it to form a protective coating on the gastric mucosa. For adrenal support, whole licorice is best taken in the morning to align with the body’s natural cortisol rhythm, with a possible second dose at midday if needed. For respiratory conditions, consistent timing throughout the day is more important than specific timing. Taking with meals containing moderate fat content (15-25g fat) enhances absorption of fat-soluble compounds, though high-fat meals may delay absorption.

For skin conditions, consistent daily administration is crucial, as benefits typically develop gradually over several weeks of regular use. When using licorice for oral health, products should be allowed to dissolve slowly in the mouth to maximize contact time with oral tissues. The half-life of glycyrrhetinic acid (the active metabolite of glycyrrhizin) is approximately 12-20 hours, suggesting once or twice daily dosing is sufficient for maintaining therapeutic levels. Due to potential side effects with prolonged use, cycling protocols (e.g., 4-6 weeks on, 1-2 weeks off) are often recommended for whole licorice containing glycyrrhizin, particularly when used for adrenal support.

• Elevated blood pressure (common with whole licorice containing glycyrrhizin, dose and duration dependent)
• Hypokalemia (low potassium levels, can occur with regular use of glycyrrhizin-containing products)
• Fluid retention and edema (common with higher doses of whole licorice)
• Headache (occasional)
• Lethargy and fatigue (can occur with prolonged use, often related to electrolyte imbalances)
• Hormonal effects including menstrual irregularities in women and decreased testosterone in men (with prolonged use)
• Muscle weakness or cramping (related to potassium depletion)
• Mild digestive discomfort (occasional)
• Allergic reactions (rare, more common in individuals allergic to plants in the Fabaceae family)

• Hypertension (uncontrolled high blood pressure)
• Heart failure or other cardiovascular disorders
• Kidney disease
• Liver disorders
• Hypokalemia (low potassium levels)
• Pregnancy (glycyrrhizin-containing licorice may increase risk of preterm labor)
• Estrogen-sensitive conditions including certain cancers, endometriosis, or uterine fibroids
• Diabetes (may affect blood glucose levels)
• Hypertonia (increased muscle tension)
• Cholestatic liver disorders or cirrhosis
• Known allergy to licorice or plants in the Fabaceae family

• Antihypertensive medications (licorice may reduce effectiveness)
• Diuretics (increased risk of potassium depletion)
• Digoxin (increased risk of toxicity due to potassium depletion)
• Corticosteroids (additive effects)
• Oral contraceptives containing estrogen (increased risk of side effects)
• Anticoagulants and antiplatelet drugs (potential interaction affecting blood clotting)
• MAO inhibitors (theoretical interaction)
• Antidiabetic medications (may affect blood glucose control)
• Potassium supplements (opposing effects)
• NSAIDs (potential increased risk of gastric side effects)
• Cytochrome P450 substrate drugs (potential altered metabolism)

For whole licorice containing glycyrrhizin: The European Scientific Committee on Food established that 100 mg/day of glycyrrhizin (approximately 50 g of licorice candy or 3-5 g of root) represents a safe upper limit for most healthy adults. However, sensitive individuals may experience side effects at lower doses. The World Health Organization suggests limiting glycyrrhizin intake to no more than 100 mg/day. Continuous use should generally be limited to 4-6 weeks unless under professional supervision.

For DGL (deglycyrrhizinated licorice): No specific upper limit has been established, as the removal of glycyrrhizin eliminates most safety concerns. DGL is generally considered safe for long-term use at recommended doses (up to 3-4 g daily).

Licorice root (Glycyrrhiza glabra) is regulated as a dietary supplement in the United States. It has not been approved as a drug for any specific health conditions. As with other dietary supplements, the FDA does not review licorice products for safety or efficacy before they are marketed. Manufacturers are responsible for ensuring their products are safe before marketing and that product labels are truthful and not misleading.

Licorice is included in the FDA’s GRAS (Generally Recognized As Safe) list for use as a flavoring agent in foods and beverages, but this designation applies specifically to its use as a flavoring in small amounts, not to its medicinal applications. The FDA has issued warnings about the potential health risks of consuming large amounts of licorice, particularly for people with certain medical conditions like heart disease, kidney disease, or high blood pressure.

Eu: In the European Union, licorice root is approved for use in traditional herbal medicinal products under the Traditional Herbal Medicinal Products Directive (2004/24/EC) for specific indications including digestive complaints and as an expectorant for coughs associated with colds. The European Medicines Agency (EMA) has published a community herbal monograph on Glycyrrhiza glabra, outlining approved uses, contraindications, and safety considerations. The EMA recommends that products containing more than 100 mg glycyrrhizin per day should carry warnings about potential side effects. For food applications, the EU Scientific Committee on Food has established that regular consumption of more than 100 mg/day of glycyrrhizin may lead to adverse effects.

Canada: Health Canada has listed Glycyrrhiza glabra in the Natural Health Products Ingredients Database with a medicinal ingredient role. It is allowed for use in Natural Health Products with appropriate claims related to digestive health, respiratory health, and as an anti-inflammatory. Products containing whole licorice must carry warnings about potential side effects with prolonged use. Health Canada has established a maximum daily dose of 15 g of dried root or equivalent preparations, not to exceed 600 mg of glycyrrhizin daily.

Australia: The Therapeutic Goods Administration (TGA) permits Glycyrrhiza glabra in listed complementary medicines (AUST L). It is included in the Australian Register of Therapeutic Goods (ARTG) for various traditional uses. The TGA requires warning statements on products containing significant amounts of glycyrrhizin regarding potential side effects and contraindications.

Japan: In Japan, licorice (Glycyrrhiza uralensis and G. glabra) is approved as a Kampo medicine ingredient (traditional Japanese herbal medicine) and is included in numerous approved Kampo formulations. The Japanese Pharmacopoeia includes monographs for licorice root and processed licorice root. The Ministry of Health, Labour and Welfare regulates its use in both medicinal and food applications.

China: Licorice root (Gan Cao) is officially listed in the Chinese Pharmacopoeia and is one of the most commonly used herbs in Traditional Chinese Medicine. The China Food and Drug Administration regulates its use in both traditional medicine formulations and as a food ingredient. Chinese regulations distinguish between raw licorice root and honey-fried licorice root (Zhi Gan Cao), which are considered to have different therapeutic properties.

Low

Dried root pieces: $0.10-0.30 per day; Dried root powder: $0.15-0.40 per day; DGL tablets/capsules: $0.30-0.70 per day; Standardized extract: $0.40-0.90 per day; Licorice tea bags: $0.20-0.50 per day

Licorice root offers excellent value for its diverse health benefits, being one of the more affordable medicinal herbs on the market. This is partly due to its widespread cultivation and the relatively high yield of active compounds from the roots. For digestive applications, DGL represents a particularly cost-effective option compared to many over-the-counter and prescription medications for acid reflux, gastritis, and ulcers. While the initial response may be slower than with pharmaceutical options, the long-term value is enhanced by the minimal side effect profile of DGL and its ability to address underlying mucosal protection rather than just symptom suppression.

For respiratory conditions, licorice tea and extracts provide affordable options for soothing irritated mucous membranes and supporting expectoration. The cost-effectiveness is particularly favorable for chronic, recurring conditions that would otherwise require ongoing pharmaceutical intervention. When comparing different forms, whole root and root powder are the most economical options but require more preparation time and may have variable potency. DGL products, while slightly more expensive, offer the advantage of removing glycyrrhizin, making them safer for long-term use and eliminating the need for monitoring blood pressure or electrolyte levels.

Standardized extracts provide more consistent active compound content and potentially better quality control, justifying their moderately higher cost. Licorice tea bags offer a convenient and affordable option for mild respiratory and digestive support, though they typically contain lower concentrations of active compounds than dedicated supplements. Organic certified products typically cost 20-30% more than conventional ones but offer better quality assurance and reduced pesticide exposure. When considering the versatility of licorice – its applications spanning digestive, respiratory, immune, adrenal, and skin health – the overall value proposition is strong, particularly for individuals who can benefit from multiple properties of the herb.

The cost-effectiveness is further enhanced by licorice’s traditional role as a synergist that can improve the efficacy of other herbs when used in combinations. Overall, licorice represents one of the more cost-effective medicinal herbs available, with DGL offering particularly good value for digestive applications due to its enhanced safety profile for long-term use.

Dried root pieces: 2-3 years when properly stored; Dried root powder: 1-2 years; Standardized extracts: 2-3 years; DGL products: 2-3 years; Capsules and tablets: 2-3 years when properly stored; Tinctures: 3-5 years; Licorice tea bags: 1-2 years

Store in airtight, opaque containers protected from light, heat, and moisture. Dried root pieces and powder should be kept in dark glass containers or opaque packaging. Capsules and tablets should remain in their original containers with desiccant packets if provided. Tinctures should be stored in dark glass bottles with tight-fitting caps.

Avoid exposure to direct sunlight or high temperatures, which can accelerate degradation of glycyrrhizin, flavonoids, and other active compounds. Traditional Chinese medicine recommends storing licorice in cool, dry places, often with specific instructions to keep it away from strong odors as the root can absorb aromatic compounds from the environment. Refrigeration is not necessary but can extend shelf life, particularly in hot and humid climates. For long-term storage of dried roots, traditional methods include adding a few neem leaves or bay leaves to prevent insect infestation.

Exposure to moisture promotes hydrolysis of glycosides and increases risk of microbial growth and mycotoxin formation, Light exposure, particularly UV light, accelerates degradation of flavonoids and other photosensitive compounds, High temperatures (above 30°C/86°F) significantly increase the rate of degradation of most active compounds, Oxidation occurs gradually with air exposure, affecting flavonoids and other polyphenols, Enzymatic degradation can occur in improperly dried plant material, Microbial contamination can lead to degradation of active compounds and production of potentially harmful metabolites, pH extremes affect stability of glycyrrhizin and other compounds; neutral to slightly acidic conditions are most stable, Repeated freeze-thaw cycles can disrupt cellular structures in liquid preparations, potentially affecting stability, Metal ions, particularly iron and copper, can catalyze oxidation reactions, Long-term storage gradually reduces potency even under optimal conditions due to slow oxidation and molecular rearrangement of unstable compounds

Synthesis Methods

Natural Sources

Quality Considerations

Licorice root (Glycyrrhiza glabra) has one of the longest and most widespread histories of use among medicinal herbs, spanning over 4,000 years across multiple civilizations. The earliest documented medicinal use appears in ancient Assyrian clay tablets (circa 2300 BCE) and Egyptian papyri, including the Ebers Papyrus (circa 1550 BCE), where it was recommended for respiratory ailments, liver problems, and as a general tonic. The herb gained such importance in ancient Egypt that quantities were found in King Tutankhamun’s tomb, intended to accompany the pharaoh into the afterlife. In traditional Chinese medicine (TCM), where licorice is known as ‘Gan Cao’ (sweet grass), its use dates back to at least the Shang dynasty (1766-1122 BCE).

The Divine Farmer’s Classic of Materia Medica (Shen Nong Ben Cao Jing), compiled around 200 CE, listed licorice as a ‘superior’ herb that could be taken long-term without toxicity. In TCM, licorice is considered unique for its ability to harmonize and enhance the effects of other herbs in formulations, earning it the title ‘The Great Adjudicator.’ It appears in more Chinese herbal formulas than any other single herb, often in small amounts to balance and enhance the overall formula. In Ayurvedic medicine of ancient India, licorice (known as ‘Yashtimadhu’ or ‘sweet stick’) has been used for over 3,000 years. The Charaka Samhita and Sushruta Samhita (circa 1000-500 BCE) describe it as a rejuvenative tonic for the respiratory system, a demulcent for the digestive tract, and a remedy for inflammatory conditions.

In Ayurvedic classification, licorice is considered to have sweet taste (‘Madhura’), cooling energy (‘Shita Virya’), and sweet post-digestive effect (‘Madhura Vipaka’). Greek and Roman physicians further expanded licorice’s medicinal applications. Hippocrates (circa 400 BCE) recommended it for asthma and dry cough. Theophrastus, Dioscorides, and Pliny the Elder all documented its medicinal properties.

The Roman naturalist Pliny noted that licorice could clear the voice, alleviate thirst, and heal wounds. The Greek name ‘glykyrrhiza,’ meaning ‘sweet root,’ gave rise to the botanical name Glycyrrhiza. During the Middle Ages, licorice remained important in European monastic medicine, with cultivation spreading to monastery gardens. The 12th-century German abbess and herbalist Hildegard of Bingen recommended licorice for respiratory and digestive complaints.

By the 15th century, licorice was being cultivated commercially in England, particularly around Pontefract in Yorkshire, where the famous Pontefract cakes (small, stamped licorice lozenges) originated. Beyond medicine, licorice has played various cultural roles throughout history. It was used to flavor drinks in ancient Egypt, as a sweetener before the widespread availability of sugar in Europe, and as a flavoring agent for tobacco. During World War II, Dutch pharmacist and confectioner Jan Frijling developed a method to extract licorice’s sweet compounds while removing the glycyrrhizin, creating what we now know as DGL (deglycyrrhizinated licorice).

This innovation allowed for the therapeutic benefits of licorice for digestive issues without the potential side effects of glycyrrhizin. The modern scientific understanding of licorice’s mechanisms, particularly the discovery of glycyrrhizin’s effects on cortisol metabolism in the 1950s, has validated many traditional uses while providing new insights into both its therapeutic potential and safety considerations.

Jiang K, Huang W, Yang XN, Xu Q, Chen S, Cao J, Ma X, Cong W, Wang R, Zou Y, Cui Y. Licorice: A review of phytochemistry, pharmacology, toxicology, and relevant clinical applications. Phytotherapy Research. 2020;34(11):2829-2850., Yang R, Yuan BC, Ma YS, Zhou S, Liu Y. The anti-inflammatory activity of licorice, a widely used Chinese herb. Pharmaceutical Biology. 2017;55(1):5-18.

Glycyrrhizin for treatment of non-alcoholic steatohepatitis (NASH) (ClinicalTrials.gov: NCT03989479), Deglycyrrhizinated licorice for gastroesophageal reflux disease (GERD) (ClinicalTrials.gov: NCT04046926), Licorice flavonoids for metabolic syndrome (UMIN Clinical Trials Registry: UMIN000042567)