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Liquorice root (Glycyrrhiza glabra)

EMA-monograph herb for dyspepsia and sore throat, pharmacologically active, with meaningful blood-pressure and potassium effects at therapeutic doses.

Why

Liquorice root (Glycyrrhiza glabra) holds an EMA HMPC monograph at Well-Established Use for upper-respiratory catarrh and at Traditional Use for mild digestive symptoms. The principal active glycyrrhizin is a potent mineralocorticoid-receptor sensitiser via 11β-HSD2 inhibition, meaning sustained therapeutic doses raise blood pressure, drop potassium, and cause fluid retention. Use either DGL (glycyrrhizin removed, see separate card) for chronic use, or whole liquorice short-term and under blood-pressure monitoring.

How it works

Glycyrrhetinic acid inhibits 11β-hydroxysteroid dehydrogenase type 2, allowing cortisol to activate the mineralocorticoid receptor, the basis of both the antitussive/expectorant effect and the hypertensive side effect. Flavonoids and isoflavones provide independent mucosal protection.

Expected onset · Cough or throat soothing acute; mucosal effect over days

How to take

Dosage

Whole liquorice extract: 200–600 mg/day (delivering up to ~100 mg glycyrrhizin), short-term only, no more than 4–6 weeks without supervision.

Timing

With meals; divided 2–3 times daily

On the label

Specify glycyrrhizin content per dose. For chronic use, use DGL instead. Liquorice flavouring (food-grade) is fine; liquorice supplement doses are not casual.

Ideal for

Adults with sore throat or short-term upper-GI complaints, willing to monitor BP and not on diuretics; otherwise prefer DGL.

Safety

Causes pseudohyperaldosteronism: hypertension, hypokalaemia, oedema, muscle weakness. Avoid in hypertension, heart failure, kidney disease, hypokalaemia, pregnancy (preterm labour, possible developmental effects). Interactions with digoxin (potentiates by hypokalaemia), antihypertensives (antagonises), corticosteroids, diuretics, hormonal contraceptives. EFSA tolerable upper level: <100 mg/day glycyrrhizin from confectionery and supplements combined.

Evidence

At a glance

EMA classifies liquorice root at Well-Established Use for upper-respiratory catarrh and Traditional Use for mild dyspepsia. EFSA's review of glycyrrhizic acid set a guidance of <100 mg/day from all sources to avoid pseudohyperaldosteronism. Omar 2012 J Med Toxicol summarises documented cases of hypertension, hypokalaemia and rhabdomyolysis from sustained liquorice intake, pharmacology is meaningful, not theoretical.

Where to get it

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