One of humanity's most universally used medicinal plants, with strong evidence for GI conditions and liver support. Critical split: DGL preparations are safe long-term, while whole-root carries real cardiovascular risks.
Traditions: TCM, Ayurveda, European herbalism
Multiple traditions agree on use.
Gan Cao (甘草, 'sweet herb') — among the most frequently prescribed herbs in TCM. Used as a harmonizing agent in virtually every formula category to moderate the actions of other herbs. Also tonifies Spleen Qi, moistens Lungs, stops cough, clears heat, and relieves spasms. Honey-fried (Zhi Gan Cao) form specifically used for tonifying Qi and nourishing the heart.
Yashtimadhu (यष्टिमधु, 'sweet stick') — classified as Rasayana (rejuvenating), Sita (cooling), and Madhura (sweet). Used for cough, bronchitis, hoarseness, gastric ulcers, hyperacidity, neurological tonic, skin disorders, and reproductive health. Referenced in Charaka Samhita and Sushruta Samhita.
Licorice extracts found in Tutankhamun's tomb (~1300 BCE). Theophrastus (~300 BCE) described uses for thirst and respiratory conditions. Hildegard von Bingen (12th century) documented use for stomach and liver. German Commission E approved positive monograph for catarrh and gastric/duodenal ulcers. Warnings against use in edema and 'high blood pressure constitutions' predate modern pharmacology — entirely consistent with what we now understand about pseudoaldosteronism.
Licorice has genuine, replicable clinical evidence for GI conditions — particularly using the standardized DGL extract GutGard, which has three Phase II/III RCTs behind it. Liver enzyme reduction is confirmed by meta-analysis. Topical use for mouth ulcers has solid evidence from multiple trials. The blood pressure effects are real even at supposedly safe doses, which makes the safety picture critically important to understand.
N=50, 30 days. GutGard 75mg twice daily: 56% marked improvement vs 0% placebo (p≤0.05). Significant improvement in total symptom score, quality of life, upper abdominal fullness, and epigastric pain.
N=200, 28 days. Heartburn resolution significantly better at day 14 (p=0.017) and day 28 (p=0.005). Regurgitation improved from day 7 onward. Quality of life significantly improved.
N=100, 60 days. GutGard 150mg/day: 56% stool antigen negative vs 4% placebo. 48% negative on urea breath test. 3.73× more effective than placebo at reducing gastric H. pylori load.
N=120. Licorice 380mg twice daily added to clarithromycin-based triple therapy: 83.3% eradication vs 62.5% triple therapy alone — a meaningful clinical improvement.
6 trials, N=314. Significant pain reduction within 4 days; significant ulcer size reduction by day 8. Licorice elevated epidermal growth factor vs control. No adverse effects across all studies.
15 RCTs, N=1,367 patients with primary liver disease. ALT reduced by 15.63 U/L vs control; AST reduced by 7.37 U/L. Purified glycyrrhizic acid compounds showed greater reductions with minimal heterogeneity.
N=90 menopausal women, 8 weeks. Licorice root extract 990mg/day significantly reduced hot flash frequency and severity vs placebo. Effects returned within 2 weeks of stopping.
N=28 healthy adults, 2-week crossover. Exactly 100mg GA/day raised systolic BP by 3.1 mmHg, suppressed renin by 30%, suppressed aldosterone by 45.1%. The WHO limit produces measurable cardiovascular effects.
DGL preparations have the best clinical evidence for GI use and lack pseudoaldosteronism risk. Standardization markers: glabridin ≥3.5% w/w, total flavonoids ≥10% w/w (GutGard). For hot flashes: 990 mg/day standardized root extract for up to 8 weeks — whole-root preparation; monitor blood pressure.
Taste: Intensely, unmistakably sweet. Glycyrrhizin is 30–50× sweeter than sucrose. Also slightly earthy and anise-like. Not bitter. This is unusual — the sweetness is the active compound.
Simmer — do not just steep. Saponin extraction requires heat and time. At 5g root (4% GA), you're already above the WHO 100mg/day limit. Stay at 1–2g per cup if using regularly. Monitor blood pressure.
Full GA content; 4-week duration limit applies. Water-soluble glycyrrhizin is well extracted by ethanol-water menstruum (20–40% ethanol). Monitor blood pressure.
Local anti-inflammatory action. Minimal systemic GA exposure. Expect meaningful pain reduction within 4 days and ulcer resolution within 8 days based on trial data.
Licorice has genuine, replicable clinical evidence concentrated in two areas: gastrointestinal conditions and liver support. The evidence base is more specific than most herbs — not “general tonic,” but actual RCT-level evidence for defined conditions.
Strong evidence:
Moderate evidence:
Doesn’t work for:
Critical nuance that changes everything: The same compound that drives the clinical benefits (glycyrrhetinic acid, GA) is the one that raises blood pressure. A 2024 RCT showed that the WHO “safe” limit of exactly 100mg GA/day still raised systolic BP by 3.1 mmHg and suppressed renin and aldosterone by 30–45% in healthy young adults [Af Geijerstam 2024]. This is a strong signal that current guidelines underestimate the threshold for cardiovascular effects.
The solution is the DGL split: deglycyrrhizinated licorice retains the GI-protective flavonoids (glabridin, liquiritigenin, isoliquiritigenin) while removing the GA. All three GutGard GI trials used DGL and reported safety comparable to placebo with no BP or electrolyte effects.
Three civilizations independently arrived at the same plant, for the same conditions, with extraordinary depth of documentation.
TCM (millennia):
Ayurveda (Charaka Samhita, Sushruta Samhita):
European herbalism (3,000+ years):
Regulatory recognition: German Commission E positive monograph for respiratory catarrh and gastric/duodenal ulcers. WHO positive monograph. EMA well-established use designation. This level of convergent traditional + regulatory validation is not common.
The single most important decision is DGL vs whole-root, not dose or timing.
For GI conditions (dyspepsia, GERD, H. pylori, gastric inflammation) — use DGL:
DGL is the evidence-based choice for GI use. It removes the cardiovascular-risk compound while retaining the GI-protective flavonoids.
| Product | Dose | Duration | Indication |
|---|---|---|---|
| GutGard (glabridin ≥3.5%, flavonoids ≥10%) | 75–150 mg/day | 30–60 days in trials | Dyspepsia, GERD, H. pylori |
| DGL chewable tablets | 400–500 mg, 2–4 tablets before meals | As needed | Heartburn, gastric discomfort |
For respiratory, adrenal, or traditional tonic use — use whole root with awareness:
The dried root decoction is the WHO-referenced standard preparation:
For mouth ulcers — use topical:
Licorice is intensely, unmistakably sweet. Glycyrrhizin is 30–50× sweeter than sucrose. The decoction tastes sweet, slightly earthy, with anise-like undertones. Unlike most medicinal herbs, there’s nothing to mask — the sweetness is the active compound.
Before starting:
Week 1–2:
Week 4 assessment:
RED FLAGS — Stop immediately:
DGL preparations do not share these contraindications based on available clinical data, but caution is still reasonable during pregnancy and for anyone with severe systemic illness.
Licorice is rare among medicinal herbs: it tastes good. Intensely, distinctly sweet. The glycyrrhizin that drives the therapeutic effects is the same compound that gives it this unmistakable flavor. In the traditional world this was a feature — licorice was used to make bitter formulas more palatable across TCM, Ayurveda, and European apothecary alike.
This also means that accidental overconsumption is easy. Licorice candy, licorice-flavored teas, and licorice herbal products can stack GA intake without the user realizing it. If you’re adding licorice tea to your routine, account for any licorice confectionery you eat. At doses people find modest and pleasant, you can exceed the threshold for cardiovascular effects.
For DGL products:
For whole-root preparations:
Avoid: Licorice products with no standardization information, no GA content disclosure, and no third-party testing.
Licorice has real clinical evidence for GI conditions — not theoretical, not animal data, but Phase III RCTs with defined populations, controlled designs, and meaningful effect sizes. The 56% marked improvement rate for dyspepsia vs 0% placebo, the 83.3% H. pylori eradication rate when added to triple therapy, the liver enzyme reductions across 1,367 patients — these are genuine signals.
The split is everything:
When it works: Meaningful GI symptom relief, H. pylori clearance support, faster mouth ulcer healing, liver enzyme normalization, temporary reduction in hot flash frequency.
When to be cautious: Any hypertension, pregnancy, potassium issues, diuretic use, or renal/hepatic impairment — avoid GA-containing preparations entirely. For everyone else using whole root: 4 weeks maximum, monitor blood pressure, stay at low-end doses.
The traditional world’s warnings about licorice in people with edema and “high heat” constitutions weren’t superstition. They were correct clinical observation, centuries before anyone understood 11β-HSD2 inhibition.
Duration: DGL for GI: 4–8 weeks minimum for meaningful assessment; safe for longer use. Whole-root preparations: maximum 4 weeks without medical supervision. Topical: days to 2 weeks.
What to notice:
For GI issues, DGL is the right starting point — same therapeutic area, clinical evidence behind it, none of the cardiovascular risk. Take DGL 15 minutes before meals to maximize mucosal contact time. If using whole-root preparations for respiratory or adrenal support, stay at the low end of dosing (1–2g dried root or equivalent), stick to 4 weeks, and check your blood pressure at the start and 2 weeks in. Licorice has a different risk profile than most herbs: the effect that makes it problematic (cortisol accumulation via 11β-HSD2 inhibition) kicks in at doses that feel modest.
Generally considered: caution
Contraindications:
Pregnancy/Nursing: Contraindicated in pregnancy per EMA/HMPC and German Commission E — potential to trigger premature labor. No safety data in breastfeeding; avoid GA-containing preparations. DGL status during lactation not specifically studied.
The key safety distinction is DGL vs whole-root. DGL preparations have no measurable blood pressure or electrolyte effects across three clinical trials. Whole-root preparations carry pseudoaldosteronism risk: glycyrrhetinic acid (the active metabolite of glycyrrhizin) inhibits 11β-HSD2 in the kidney, causing cortisol to accumulate and activate mineralocorticoid receptors — producing hypertension, hypokalemia, edema, and metabolic alkalosis. A 2024 RCT showed the WHO 'safe' limit of 100mg GA/day still produces +3.1 mmHg systolic BP and 30–45% RAAS suppression in healthy young adults. The NOAEL is 2 mg/kg/day (van Gelderen 2000); the proposed ADI is 0.2 mg/kg/day (~12mg/day for a 60kg person). Drug interactions: antihypertensives (licorice counteracts them), corticosteroids (additive potassium loss), loop/thiazide diuretics (additive hypokalemia), warfarin (monitor INR). Effects are reversible upon stopping. Duration limit for whole-root: 4–6 weeks maximum without supervision.