DGL vs Whole Licorice: Why the Glycyrrhizin Form Causes Hypertension and Hypokalemia

Licorice root (Glycyrrhiza glabra) is one of the few herbal supplements that reliably causes serious adverse events at routinely-consumed doses. The mechanism is precise, the dose–response is well-characterised, and case reports of severe hypertension, hypokalemia, rhabdomyolysis, and cardiac arrhythmia from licorice candy and tea consumption appear annually in clinical journals. The distinction between whole licorice and deglycyrrhizinated licorice (DGL) is the single most important point for anyone considering it.

The biochemistry — apparent mineralocorticoid excess

Glycyrrhizin is the principal triterpenoid saponin of licorice. It is hydrolysed in the gut to glycyrrhetinic acid, a potent inhibitor of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) in the kidney. 11β-HSD2 normally inactivates cortisol to cortisone at the renal tubule, protecting the mineralocorticoid receptor (which has equal affinity for cortisol and aldosterone) from being activated by cortisol. When 11β-HSD2 is inhibited, cortisol acts on the mineralocorticoid receptor, producing sodium retention, potassium wasting, hypertension, and metabolic alkalosis — clinically indistinguishable from hyperaldosteronism, but with low aldosterone [1].

The dose threshold

Pharmacokinetic studies established that as little as 50 mg/day of glycyrrhizin can raise blood pressure measurably in susceptible individuals over a few weeks. A daily intake of 100 mg or more is associated with clinically important hypertension and hypokalemia in normotensive adults [2]. To put this in perspective: standard black licorice candy contains roughly 1–4% glycyrrhizin; eating 30–50 g daily can deliver enough glycyrrhizin to produce hypertensive crises. Licorice "tea" varies widely by brand and brewing strength.

FDA and EFSA positions

The FDA has issued public-health advisories about adults consuming more than 2 oz of black licorice daily for two weeks. EFSA's scientific opinion concluded that regular intakes above 100 mg/day of glycyrrhizin should be avoided [3]. Several European countries require warning labels on licorice candy.

Clinical case series

Published case reports describe hypertensive crises with potassium below 2.0 mmol/L, ventricular arrhythmias, rhabdomyolysis, and Torsades de pointes — from licorice candy, herbal teas, or "natural" licorice supplements. Most cases resolve over 1–2 weeks of withdrawal but the cortisol-mediated effect can persist longer; spironolactone has been used to treat severe cases [4].

DGL — deglycyrrhizinated licorice — is different

Deglycyrrhizinated licorice is processed to remove glycyrrhizin, retaining the flavonoids and other phenolic compounds. DGL does not produce mineralocorticoid effects at typical supplement doses (usually defined as ≤2 mg residual glycyrrhizin per dose). It is sold for upper-GI complaints — dyspepsia, mild reflux, and aphthous ulcers — with modest clinical evidence supporting use [5]. The clinically important point is reading labels: products marked "licorice extract" without "DGL" or "glycyrrhizin-free" likely contain enough glycyrrhizin to cause harm with chronic use.

Who should be especially careful

People with hypertension, heart failure, chronic kidney disease, hypokalemia, or on potassium-wasting diuretics, ACE inhibitors with hyperkalemia risk, digoxin, or QT-prolonging drugs are at higher risk. Pregnant women have an additional concern: high glycyrrhizin intake in pregnancy has been associated with shorter gestation and cognitive/behavioural effects in offspring in Finnish cohort studies. Avoiding glycyrrhizin-containing licorice in pregnancy is recommended.

Practical guidance

For routine GI symptomatic use, DGL (≤2 mg residual glycyrrhizin per dose) is the safe form. For ulcers, reflux, or mouth ulcers, 4–6 weeks of trial use is reasonable. For any other indication (adrenal "support," cortisol "balance," cough), the glycyrrhizin-containing whole-extract products are not safe for chronic use and the clinical claims are not supported. People who eat black licorice candy in any quantity should be aware that periodic blood pressure and potassium checks are sensible if intake is regular.

How to spot glycyrrhizin in a product

Reading labels matters because licorice products are inconsistently described. Reliable indicators of safe DGL: explicit "DGL" or "deglycyrrhizinated" on the label, residual glycyrrhizin specified at ≤2 mg per dose, and absence of "Glycyrrhiza glabra root extract" without DGL qualification. Reliable indicators of glycyrrhizin-containing licorice: "licorice root extract," "Glycyrrhiza glabra," black licorice candy ingredient lists naming licorice extract, and herbal teas with licorice in the ingredient panel. Some "adrenal support" formulas combine licorice with rhodiola or ashwagandha and rely on the mineralocorticoid effect for an apparent energy benefit; the practical reality is they raise BP and lower potassium. Daily intake assessment should sum across sources — tea, candy, and supplement — because cumulative dose is what matters.