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Ayurveda · Traditional Chinese medicine · Western herbalism

LicoriceGlycyrrhiza glabra

Whole root and DGL are different products: 18 studies show whole root raising systolic pressure 5.45 mmHg; a DGL ulcer trial found no healing effect.

Botanical name
Glycyrrhiza glabra
Part used
root and rhizome
Also called
Sanskrit Yashtimadhu, Madhuyashti; Hindi Mulethi; pinyin Gan cao (甘草); Liquorice, Sweet root, Glycyrrhiza uralensis (Chinese licorice), DGL (deglycyrrhizinated licorice)
Used in
Ayurveda, Traditional Chinese medicine, Western herbalism
Taken for
Reflux and heartburn, Indigestion, The gut lining, Cramping and pain
Sold as
tea, capsules, chewable tablet, powder, extract, lozenges

Licorice, the plant and the part used

Licorice is the sweet root of Glycyrrhiza glabra and two close relatives, G. uralensis and G. inflata, which supply most Chinese licorice. The root is dug, dried and sold as pieces, powder, tea, a soft extract or a standardized capsule. Its sweetness comes from glycyrrhizin, which a review describes as roughly 50 times sweeter than sugar, and which is also responsible for the herb’s main safety problem.

Two products carry the name, and they should not be mixed up. Whole-root licorice keeps its glycyrrhizin and is what herbal teas, lozenges, candy and most traditional preparations contain. Deglycyrrhizinated licorice (DGL) is root extract from which most of the glycyrrhizin has been removed, sold as chewable tablets, capsules and powders for stomach complaints. The older medical literature on DGL used a tablet called Caved-S; an Irish medicines record lists it as DGL extract with aluminium hydroxide, magnesium carbonate and sodium bicarbonate, so those trials tested DGL together with antacids.

Some supplements are flavonoid-rich extracts, a third category, with their own small trials.

Traditional uses, in their own terms

Ayurveda (about Ayurveda)

Ayurveda knows licorice as yashtimadhu, literally the sweet stick. A table of classical properties lists it as sweet (madhura), heavy, unctuous and cooling, with a reducing effect on pitta and vata, and a review of the tradition describes it as a purgative, an ulcer-protecting medicine, and a cough and expectorant remedy. An Ayurvedic clinical study of 40 people with amlapitta, the tradition’s name for a pattern of sour belching, burning in the chest and throat, and nausea, gave root powder for two weeks and recorded relief of those symptoms. Amlapitta is the tradition’s own category, not a measurement of the body, and the study compared two root powders without a placebo.

Traditional Chinese medicine (about TCM)

Gan cao is classed as sweet, entering the heart, lung, spleen and stomach channels. Texts distinguish raw slices, used to clear heat and ease phlegm, from honey-fried licorice (zhi gan cao), which the tradition uses to tonify the spleen and harmonize the stomach, for what it calls spleen-stomach weakness with fatigue. It is also the herb that is added to formulas to harmonize the other ingredients. A clinic summary gives a decoction dose of 1.5 to 9 g and lists hypertension, cirrhosis, chronic kidney insufficiency and pregnancy as contraindications.

Western herbalism

A review reports that licorice was the most prescribed herb in ancient Egypt, Greece and Rome, and notes a French herbal tea traditionally used to aid digestion. The European Medicines Agency’s herbal committee lists liquorice root as a traditional herbal medicine for the relief of digestive symptoms including burning sensation and dyspepsia, and as an expectorant in cough with a cold, based on long-standing use alone.

Compounds, and what the laboratory says about them

Glycyrrhizin’s metabolites, including glycyrrhetinic acid, suppress 11-beta-hydroxysteroid dehydrogenase type 2, the enzyme that converts cortisol to cortisone, so cortisol acts on mineralocorticoid receptors, causing sodium and water retention and potassium loss. That mechanism explains the blood pressure effect of whole root. The root also contains flavonoids such as liquiritin and glabridin (0.08 to 0.35% of dry root in one review). DGL is made to remove the glycyrrhizin.

Trials in people, with the numbers

The strongest numbers for licorice are about harm. A meta-analysis of 18 studies (337 people) of products with at least 100 mg of glycyrrhizic acid a day found systolic pressure up 5.45 mmHg (95% CI 3.51 to 7.39), diastolic up 3.19 mmHg, plasma potassium down 0.33 mmol/L, and lower renin and aldosterone; blood pressure rose with dose.

For DGL, the trial record is old and mostly negative. A double-blind crossover trial of DGL extract (760 mg three times daily for 4 weeks, 38 and 30 patients in the two periods) found no healing effect on gastric ulcers against placebo. A 100-patient endoscopic trial found Caved-S (six tablets a day) and cimetidine equivalent, at roughly 63% healed at 6 weeks and 91% at 12; because Caved-S also contained antacids, that comparison cannot isolate DGL. We could not find a randomized trial of chewable DGL tablets for heartburn or reflux.

For dyspepsia, a proprietary glycyrrhiza extract (75 mg twice daily for 30 days) lowered total symptom scores more than placebo on days 15 and 30; the Cochrane review of non-Chinese herbal medicines for functional dyspepsia rated this as one 50-person study, moderate certainty (standardized mean difference −1.86, 95% CI −2.54 to −1.19). In 120 people with H. pylori, adding licorice to clarithromycin triple therapy for two weeks gave a favorable response in 83.3% against 62.5%.

StudyDoseWhat it found
Meta-analysis of 18 studies, 337 people, products with 100 mg or more glycyrrhizic acid a day (safety) PMID 28660884Chronic daily intakeSystolic BP +5.45 mmHg, diastolic +3.19; potassium -0.33 mmol/L; renin and aldosterone lower
Randomized double-blind crossover, 38 and 30 gastric ulcer patients (DGL) PMID 4584640760 mg DGL extract three times daily, 4 weeksNo difference from placebo in ulcer area or complete healing; no side effects
Single-blind endoscopic trial, 100 patients with gastric ulcer (Caved-S, DGL plus antacids, vs cimetidine) PMID 7042486Six tablets a day vs cimetidine 1 g a dayNo significant difference; about 63% healed at 6 weeks and 91% at 12 weeks
Randomized placebo-controlled trial in functional dyspepsia (glycyrrhiza extract; Cochrane: 50 participants) PMID 2174789375 mg twice daily for 30 daysTotal symptom score lower than placebo on days 15 and 30 (P at or under 0.05); well tolerated
Randomized trial, 120 patients with H. pylori, licorice added to triple therapy PMID 27614124Two weeks alongside clarithromycin regimenFavorable response 83.3% vs 62.5% without licorice
Ayurvedic comparison, 40 patients with amlapitta (Yashtimadhu vs Jethimala root powder, no placebo) PMID 27011716Root powder with water for 2 weeksBurning in chest and throat relieved 69%, sour belching 67.64%, nausea 65.35% in the Yashtimadhu group

The doses on record

The European monograph’s traditional-use doses for digestive symptoms are a tea of 1.5 to 2 g of comminuted root in 150 ml of boiling water, one cup after meals, 2 to 4 times daily (3 to 8 g a day), or a soft extract at 32 mg two to three times daily (64 to 96 mg a day, up to 160 mg), for no more than 4 weeks.

Trials used 75 mg twice daily of a glycyrrhiza extract for 30 days, 760 mg of DGL extract three times daily, and six Caved-S tablets a day. A TCM clinic summary lists 1.5 to 9 g as a decoction. The Ayurvedic study gave root powder with water for two weeks.

None of this is a dose recommendation. It is what the literature used, set down so a label can be compared with it; a pharmacist or clinician decides what applies to you.

The safety record

Whole-root licorice is the safety concern. The European monograph says liquorice medication is not advised in people with hypertension, kidney, liver or cardiovascular disease or low potassium, because they are more sensitive. It reports overdose with prolonged use (more than 4 weeks) or high intake, with water retention, low potassium, high blood pressure and heart rhythm disorders as the serious events. Intakes that triggered mineralocorticoid excess syndromes ranged from 1.5 to 250 g a day in one review, so individual sensitivity varies widely.

The monograph does not advise use in pregnancy, for women who could become pregnant without contraception, or while breastfeeding (glycyrrhizin is detectable in breast milk), and use under 18 is not established. DGL is made to remove glycyrrhizin; we could not find a trial that measured blood pressure or potassium on DGL, and the DGL ulcer trial reported no side effects.

Medicines it can interact with

The European monograph says liquorice root may counteract blood-pressure medicines, and should not be combined with diuretics, cardiac glycosides, corticosteroids, stimulant laxatives or other drugs that deplete potassium, because the effects stack. It also reports that 300 mg a day of glycyrrhizin for 14 days modestly lowered exposure to drugs cleared by CYP3A4, such as midazolam and omeprazole, and advises caution with such drugs. These findings concern glycyrrhizin-containing products. The catalog’s own drug rules for licorice are listed automatically on this page.

The interaction rules the quiz applies to licorice

These are the medicines the quiz pairs with a caution or an exclusion for this herb, taken from published interaction references:

Where licorice turns up in the catalog

Licorice appears on the labels below, alone or inside a blend; each product page gives the printed amount, the evidence for that product and the review picture.

Inno Supps Inno Cleanse 4.1 out of 5 from 12,407 ratings from Amazon · $1.33 a day Emma Relief Daily Digestive Supplement 4 out of 5 from 11,119 ratings from Amazon · $2.00 a day Gundry MD Total Restore 4.1 out of 5 from 9,333 ratings from Amazon · $2.33 a day Bigelow Lemon Ginger Plus Probiotics Herbal Tea 4.7 out of 5 from 9,016 ratings from Amazon · $0.20 a day Natural Factors Chewable DGL 4.4 out of 5 from 8,009 ratings from Amazon · $22.37 for 180 tablets, about $0.12 to $0.37 a day depending on frequency Liver Medic Leaky Gut Repair 4.1 out of 5 from 3,474 ratings from Amazon · $1.00 per day at two capsules; the label’s advanced dose of four to six is $2.00 to $3.00 Yogi Lemon Ginger Tea 4.7 out of 5 from 3,114 ratings from Amazon · $0.23 per cup on Amazon ($3.68 for 16 bags); $0.31 on iHerb and $0.44 for a single box on the brand’s site Terra Origin Healthy Gut Powder 4.3 out of 5 from 1,990 ratings from Amazon · $1.02 a day Yogi Stomach Ease Tea 4.7 out of 5 from 1,375 ratings from Amazon · $0.28 per cup on the Amazon 6-pack; $0.44 for a single box on the brand site Clean Nutra GI Defend 4.4 out of 5 from 1,152 ratings from Amazon · $1.00 a day DelighTeas Ayurvedic Stomach Relief & Happy Liver Tea 4.6 out of 5 from 1,040 ratings from Amazon · $0.34 a day NanoRevive EsoRepair Esophageal & Stomach Liquid 3.9 out of 5 from 1,003 ratings from Amazon · $2.00 a day

23 more entries list it; the full catalog is grouped by the job each product does.

Which product, for your symptoms?

The quiz weighs your symptoms and medicines against every product researched here, licorice products included, and shows its working.

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The questions that come up

What is the difference between licorice and DGL?

DGL is licorice root extract with most of the glycyrrhizin removed. Whole root keeps glycyrrhizin, which raised systolic pressure 5.45 mmHg and lowered potassium in a meta-analysis of 18 studies. The DGL trials we found were done in the 1970s and 1980s, with a tablet that also contained antacids.

Does DGL heal stomach ulcers?

A double-blind crossover trial of DGL extract found no healing effect on gastric ulcers against placebo. A separate 100-patient trial found Caved-S, which also contained antacids, equivalent to cimetidine. The trials do not isolate DGL, and we could not find a modern placebo-controlled trial.

Can licorice tea raise blood pressure?

Whole-root licorice can. The effect depends on the glycyrrhizin dose and the person, with the European monograph advising against it in hypertension and limiting use to 4 weeks. Teas vary in strength, so the amount of glycyrrhizin per cup is not fixed.

Is licorice the same as Chinese gan cao?

Gan cao is Chinese licorice, mostly from the species Glycyrrhiza uralensis and Glycyrrhiza inflata, while Western products usually use Glycyrrhiza glabra. The European monograph covers all three. In TCM it is also added to many formulas to harmonize the other herbs, which is a different role from the single-herb products sold in the West.

Has licorice been tested for H. pylori?

In 120 patients, adding licorice to standard triple therapy for two weeks gave a favorable response in 83.3% against 62.5%. The trial was small, and the licorice was an add-on to the antibiotic regimen, not a replacement for it.

Sources