Nature has long served as an important source of therapeutic substances, providing medicinal plants rich in valuable phytochemicals. Licorice, scientifically known as Glycyrrhiza glabra, belongs to the Fabaceae (Leguminosae) family and is widely used in Ayurvedic and other traditional systems of medicine. It is distributed across several regions of Asia and Europe and is believed to have originated in the Middle East. Licorice is also one of the commercially important medicinal plants, with applications in the food, pharmaceutical, cosmetic, and tobacco industries.1
In traditional medicine, licorice is regarded as an essential herbal medicine and is frequently incorporated into multi-herb formulations to complement the effects of other ingredients. It is also valued as a natural sweetener and flavouring agent. The roots and rhizomes contain a diverse range of constituents, including amino acids, proteins, polysaccharides, sugars, minerals, pectin, sterols, gums, and resins. Its therapeutic potential is primarily attributed to bioactive compounds, such as glycyrrhizin, glycyrrhetinic acid, glabridin, liquiritin, and other flavonoids.2 These constituents have demonstrated potential antioxidant, anti-inflammatory, antimicrobial, and mucosal-protective effects. Although licorice has a long history of traditional use, further clinical research is needed to establish the effectiveness and safety of its various therapeutic applications.
Active constituents and mechanisms of action
Licorice contains several classes of biologically active compounds:
- Glycyrrhizin: A triterpenoid saponin associated with anti-inflammatory and antiviral activities. Its metabolite, glycyrrhetinic acid, also influences steroid metabolism
- Flavonoids: Compounds, such as glabridin, liquiritin, and isoliquiritigenin contribute to antioxidant and anti-inflammatory effects
- Polyphenols: These compounds may help neutralise reactive oxygen species and reduce oxidative stress
- Polysaccharides: These have demonstrated potential immunomodulatory activities
These constituents may act through multiple pathways, including modulation of inflammatory mediators, oxidative stress, microbial activity, and cellular signalling. Their effects depend on the species, extraction method, composition, and concentration of the preparation.
Beneficial effects of licorice
Anti-inflammatory and antioxidant properties:
Licorice contains flavonoids and triterpenoids that may help reduce inflammation and oxidative stress. Experimental studies suggest that these compounds can influence inflammatory signalling pathways and reduce the production of certain inflammatory mediators. These properties have generated interest in licorice-derived compounds for inflammatory disorders and tissue protection.3 However, their effectiveness in routine clinical practice requires further validation.
Respiratory health:
Licorice has traditionally been used to manage cough and throat irritation. Its demulcent properties may help soothe irritated mucosal surfaces, while its expectorant activity has been investigated for supporting mucus clearance. Glycyrrhizin and other constituents have also demonstrated anti-inflammatory effects. Nevertheless, evidence supporting licorice as a standalone treatment for respiratory diseases remains limited.
Gastrointestinal health:
Licorice has a long history of use in traditional medicine for digestive complaints. Laboratory studies suggest that certain constituents may exert protective effects on the gastric mucosa through anti-inflammatory and antioxidant mechanisms. Deglycyrrhizinated licorice (DGL), which has most of its glycyrrhizin removed, is marketed for digestive health. However, high-quality clinical evidence confirming its effectiveness for peptic ulcers, gastroesophageal reflux disease, or other gastrointestinal conditions remains insufficient.
Oral health and mucosal protection:
One of the more promising clinical applications of licorice is in oral care. Clinical studies indicate that licorice-containing mouth rinses or gargles may reduce pain and ulcer size in patients with recurrent aphthous ulcers. Licorice preparations have also been investigated for reducing postoperative sore throat following endotracheal intubation. Further studies are needed to establish standardised formulations and treatment protocols.
Antimicrobial and antiviral activity:
Licorice-derived compounds have demonstrated antibacterial, antifungal, and antiviral activities in laboratory studies. Glycyrrhizin and selected flavonoids may interfere with microbial replication, inflammatory responses, or other cellular processes involved in infection. These findings support continued investigation into potential therapeutic applications. However, laboratory activity does not establish clinical efficacy, and licorice should not be used as a substitute for appropriate antimicrobial or antiviral treatment.
Skin health and wound healing:
Topical licorice extracts have attracted interest in dermatology because of their potential anti-inflammatory and antioxidant effects.4 Glabridin and other flavonoids have been investigated for effects on skin pigmentation and inflammatory responses. Preliminary clinical research has also explored licorice-containing preparations for atopic dermatitis and burn healing. Although these findings are encouraging, more rigorous studies are needed to determine their effectiveness, optimal formulations, and long-term safety.
Neuroprotective and metabolic effects:
Emerging preclinical evidence suggests that licorice-derived compounds may have neuroprotective properties through antioxidant activity, modulation of inflammatory pathways, and effects on neuronal signalling. Other experimental studies have investigated potential antidiabetic effects involving glucose metabolism and insulin-related pathways. These findings may provide directions for future drug development, but evidence is not sufficient to recommend licorice for treating neurological disorders or diabetes.
Conclusion
Licorice is a medicinal plant with a diverse range of potentially beneficial biological activities. Its most promising areas of investigation include oral mucosal protection, anti-inflammatory effects, skin applications, and antimicrobial activity. However, evidence supporting many proposed benefits remains preliminary, and clinical efficacy depends on the preparation and indication. Appropriate patient selection, product standardisation, and awareness of glycyrrhizin-related adverse effects are essential when considering licorice in integrative healthcare.
Reference:
- Wahab S, Annadurai S, Abullais SS, et al. Glycyrrhiza glabra (Licorice): A Comprehensive Review on Its Phytochemistry, Biological Activities, Clinical Evidence and Toxicology. Plants (Basel). 2021;10(12):2751. Published 2021 Dec 14. doi:10.3390/plants10122751 https://pmc.ncbi.nlm.nih.gov/articles/PMC8703329/
- Ji X, Liu N, Huang S, Zhang C. A Comprehensive Review of Licorice: The Preparation, Chemical Composition, Bioactivities and Its Applications. Am J Chin Med. 2024;52(3):667-716. doi:10.1142/S0192415X24500289 https://pubmed.ncbi.nlm.nih.gov/38716617/
- Chen L, Gong J, Yong X, Li Y, Wang S. A review of typical biological activities of glycyrrhetinic acid and its derivatives. RSC Adv. 2024;14(10):6557-6597. Published 2024 Feb 22. doi:10.1039/d3ra08025k https://pmc.ncbi.nlm.nih.gov/articles/PMC10882267/
- Ciganović P, Jakimiuk K, Tomczyk M, Zovko Končić M. Glycerolic Licorice Extracts as Active Cosmeceutical Ingredients: Extraction Optimization, Chemical Characterization, and Biological Activity. Antioxidants (Basel). 2019;8(10):445. Published 2019 Oct 1. doi:10.3390/antiox8100445 https://pmc.ncbi.nlm.nih.gov/articles/PMC6826613/