What happens when you take lisinopril with licorice?
Lisinopril is an ACE inhibitor that lowers blood pressure by blocking the renin-angiotensin-aldosterone system (RAAS). Licorice root contains glycyrrhizin (also called glycyrrhizic acid), which after digestion becomes glycyrrhetinic acid. That compound inhibits an enzyme called 11-beta-hydroxysteroid dehydrogenase type 2 in the kidney, which normally inactivates cortisol so that it doesn't activate the mineralocorticoid receptor. When the enzyme is blocked, cortisol acts like aldosterone, telling the kidneys to retain sodium and water while flushing potassium out.
The clinical effect of this pseudoaldosteronism is exactly what someone on lisinopril is trying to avoid: rising blood pressure, fluid retention, and falling serum potassium. Licorice is pushing one direction while the medication pushes the other, and at meaningful doses licorice can overcome lisinopril's effect, leading to apparent treatment failure and unexplained blood pressure spikes.
Why is this important?
The dose-response relationship for licorice and blood pressure is well documented. Studies in healthy volunteers consuming licorice in amounts equivalent to 75 to 540 mg of glycyrrhetinic acid per day for two to four weeks showed systolic blood pressure increases of 3.1 to 14.4 mmHg. Plasma potassium dropped by 0.3 to 1.5 mEq/L in nearly all participants in higher-dose studies. In people with preexisting hypertension or those on antihypertensive medication, even smaller doses can cause clinically meaningful effects.
Case reports have described hypertensive crisis with end-organ damage from heavy licorice consumption, including stroke, encephalopathy, and kidney injury. While most everyday exposures fall well short of those extremes, the combination of licorice with an ACE inhibitor is particularly insidious because patients often attribute rising blood pressure to medication failure rather than to a candy or herbal tea they have been consuming.
The other half of the problem is hypokalemia. Lisinopril typically raises potassium slightly through its RAAS-blocking effect. Licorice does the opposite, lowering potassium through pseudoaldosteronism. The interaction can produce confusing potassium swings - sometimes low, sometimes high if licorice is stopped suddenly while lisinopril continues. Low potassium in turn can cause muscle weakness, fatigue, cramps, palpitations, and in severe cases dangerous cardiac arrhythmias.
What should you do?
If you take lisinopril, treat licorice root and concentrated glycyrrhizin products as ingredients to avoid. Check labels on candies, teas, herbal tinctures, throat lozenges, and traditional remedies. Glycyrrhiza glabra and Glycyrrhiza uralensis are the species most commonly used. Many products labeled as licorice flavor in the United States actually use anise oil and contain no glycyrrhizin; black licorice candies that do contain real licorice extract are the more common source of trouble.
If you have been consuming licorice regularly and your blood pressure has been creeping up despite stable lisinopril dosing, stopping the licorice and rechecking blood pressure after one to two weeks is a sensible first step. Significant hypokalemia takes weeks to resolve fully after cessation, so a serum potassium check at that time is also reasonable.
If you use licorice products for digestive issues, look for deglycyrrhizinated licorice (DGL). These products have had glycyrrhizin removed during processing and are not associated with the mineralocorticoid effects that drive the blood pressure interaction. DGL is widely available as chewable tablets and is considered safe to combine with antihypertensive therapy.
Which specific products are affected?
Black licorice candy (especially imported European brands like Panda, RJ's, and Dutch dropjes) is the most common source of significant glycyrrhizin exposure. Licorice root tea, including blends marketed for digestion, adrenal support, or hormone balance, frequently contains meaningful amounts. Herbal cough drops and throat sprays with licorice root are another less obvious source.
Traditional Chinese herbal formulas often include licorice root (gancao) as a balancing ingredient; these should be reviewed with a herbalist or clinician familiar with the formulas. Some chewing tobaccos and pipe tobaccos are flavored with licorice extract. Licorice extract is also found in certain laxatives and diuretic herbal blends, and even in some bitters and amari used in cocktails.
Deglycyrrhizinated licorice products are clearly labeled DGL and contain less than 2% glycyrrhizin. These are considered safe with lisinopril for typical use.
The bottom line
Licorice raises blood pressure and lowers potassium through pseudoaldosteronism, directly working against lisinopril. Avoid black licorice candy, licorice root tea, and herbal products containing glycyrrhizin while on lisinopril. Use DGL instead if you need licorice for digestive support. If your blood pressure has been unexpectedly high, take an honest inventory of licorice-containing products before assuming the medication has stopped working.