For the stomach, the DGL form (deglycyrrhizinated licorice) avoids the effect on blood pressure. Limit licorice containing glycyrrhizin.
The deglycyrrhizinated form (DGL) relieves digestive discomfort.
View the study (RCT) →Licorice with glycyrrhizin raises blood pressure and lowers potassium.
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Licorice is the root of Glycyrrhiza glabra, a legume native to the Middle East and the eastern Mediterranean, used since antiquity as a natural sweetener (it is 30-50 times sweeter than sucrose), as a flavoring, and as a medicine; the Greek, Roman, Chinese, and Ayurvedic pharmacopoeias agree in describing it as a digestive tonic, a respiratory anti-inflammatory, and a mild adaptogen, a multiplicity of uses consistent with the chemical complexity of the root, which contains more than 400 identified compounds with documented biological activity.
The best-known active principle is glycyrrhizin (glycyrrhizic acid), responsible for the characteristic sweet taste and for most of the relevant pharmacological effects, both desirable and adverse; its ability to inhibit the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (which normally inactivates cortisol in the kidney) explains the most feared clinical complication of licorice at high or prolonged doses: high blood pressure, sodium and water retention, hypokalemia, and, in severe cases, metabolic alkalosis (pseudohyperaldosteronism), a well-documented and sometimes serious toxicity.
The most clinically used form is deglycyrrhizinated licorice (DGL), an extract from which more than 97 percent of the glycyrrhizin has been removed while retaining the flavonoids and other active components, which allows it to be used without the adverse blood-pressure-raising and mineral effects; several small studies have shown significant improvements in functional gastroesophageal reflux, dyspepsia, and peptic ulcer with doses of 380-760 milligrams of chewable DGL 20 minutes before meals.
The mechanism is multiple: stimulation of the secretion of protective gastric mucin, improved mucosal microcirculation, a slight antimicrobial effect against Helicobacter pylori, and local anti-inflammatory activity; DGL is positioned in integrative clinical practice as a reasonable option for people with functional dyspepsia or mild reflux who prefer to avoid long-term proton pump inhibitors, a preference supported by growing concerns about the adverse effects of chronic PPI use.
Licorice has traditionally been used as an expectorant and cough suppressant in respiratory infections; some studies show in vitro antiviral activity against several respiratory viruses and symptomatic improvements in pharyngitis and bronchitis with supplementation for 5-10 days, although the clinical evidence is preliminary.
Licorice is frequently prescribed in integrative medicine circles for "adrenal fatigue" or low baseline cortisol precisely because of its ability to prolong the biological half-life of endogenous cortisol (mechanism: inhibition of 11-beta-HSD2, which normally degrades it); although the entity "adrenal fatigue" is not recognized in conventional endocrinology, in people with low baseline cortisol documented by laboratory testing, licorice may provide modest symptomatic improvements, an intervention that requires monitoring of blood pressure and potassium.
For reflux or dyspepsia, DGL 380-760 mg chewable 20 minutes before meals, 3 times a day for 4-8 weeks; for respiratory use, infusion or standardized extract following the product's directions, for days rather than weeks; for adrenal indications, extracts containing glycyrrhizin (not DGL) at low doses and for short periods under medical follow-up.
The most important precaution is limiting the dose and duration of whole licorice (not DGL): chronic consumption of more than 100 milligrams per day of glycyrrhizin can produce hypertension, fluid retention, and hypokalemia, a well-documented toxicity that calls for extreme caution in people with preexisting hypertension, heart failure, or kidney disease, or who take corticosteroids, diuretics, or digitalis; licorice is contraindicated in pregnancy (an effect on fetal cognitive development has been described); "DGL" products do not carry these risks but lose some of the effects attributed to glycyrrhizin.
Information, not medical advice. Scientific evidence reflects the quality of the studies.