Licorice

Overview

Licorice is the root of Glycyrrhiza glabra, a plant whose sweet, fibrous root has been used across several traditional medical systems and is now studied in modern clinical trials. Research has looked at licorice's effects on liver enzymes in people with liver disease, blood pressure, metabolic markers in polycystic ovary syndrome (PCOS), burn wound healing, and painful mouth ulcers.

A pooled analysis of 15 randomized trials involving 1,367 people with primary liver disease found that licorice preparations lowered ALT (alanine aminotransferase, a liver enzyme used to check for liver damage) by about 15.6 U/L compared with placebo or standard care¹. A separate meta-analysis of trials on licorice's functional components and blood pressure identified measurable effects, alongside network toxicology work exploring possible mechanisms². In a randomized, double-blind trial of 66 overweight or obese women with PCOS, 1.5 g/day of licorice extract added to a low-calorie diet was compared with placebo plus the same diet over 8 weeks, with researchers tracking body composition, fasting blood sugar, insulin, and lipid levels³. A double-blinded trial in 50 patients with second-degree burns tested a hydroalcoholic licorice root gel on wound healing⁴, and a placebo-controlled trial in 54 people with painful aphthous mouth ulcers found that licorice gargle juice reduced self-reported pain scores within a day of use⁵. Traditional systems have long reached for licorice specifically for sore, irritated throats and coughs — from the Shang Han Lun's use of licorice alone as first-line treatment for throat pain (Study Study 9) to Ayurveda's classification of it among the ten "Kanthya" throat herbs (Study 11).

Dosage

Studies used varying forms and doses depending on the condition studied. For PCOS-related metabolic markers, one randomized trial used 1.5 g/day of licorice extract combined with a low-calorie diet for 8 weeks³. The liver disease meta-analysis pooled 15 RCTs using different Glycyrrhiza spp. preparations and doses, so no single standardized oral dose was reported across studies¹. Topical use has also been studied: a hydroalcoholic licorice root gel was applied to second-degree burn wounds in one trial⁴, and a licorice gargle juice was used for 1–2 days for aphthous ulcer pain relief in another⁵. The blood pressure meta-analysis examined licorice functional components across multiple trials without a single unified dose reported in this brief². No consistent standardized dosage across all uses was found in the reviewed studies.

Interactions

The reviewed studies document a link between licorice's functional components and blood pressure², suggesting a possible interaction with blood pressure medications, though the meta-analysis did not report specific drug-interaction data. The liver disease meta-analysis studied licorice's effect on liver enzymes in people with existing liver conditions¹, which could be relevant to anyone taking other medications processed by the liver, though no specific drug interactions were tested. No other drug or herb interaction data was found in the reviewed studies — anyone taking prescription medication, especially for blood pressure, heart, or liver conditions, should ask a doctor before combining it with licorice.

Traditional Use

Evidence Strength

Licorice has a solid base of clinical evidence for some uses: two meta-analyses (covering liver enzymes and blood pressure) and several randomized controlled trials support real, measurable effects in specific contexts — liver enzyme improvement, blood pressure changes, PCOS-related metabolic markers, burn wound healing, and mouth ulcer pain relief. That said, the trials vary widely in preparation, dose, and population, and none in this brief reported detailed long-term safety data, so the overall picture is consistent but still calls for larger, more standardized trials.