What happens when you take furosemide with licorice?
Furosemide (Lasix) is a powerful loop diuretic that already causes the kidneys to dump potassium. Licorice root (Glycyrrhiza glabra or Glycyrrhiza uralensis) contains glycyrrhizin, which is metabolized to glycyrrhetinic acid in the body. Glycyrrhetinic acid inhibits the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (11-beta-HSD2) in the kidney.
Normally, 11-beta-HSD2 converts cortisol into inactive cortisone so it does not stimulate the mineralocorticoid receptor. When licorice blocks this enzyme, cortisol piles up and acts like aldosterone - the body retains sodium and water, raises blood pressure, and excretes potassium into the urine. This syndrome is called apparent mineralocorticoid excess or pseudoaldosteronism.
Stacking licorice on top of furosemide adds two potassium-wasting mechanisms together. The result is a substantially higher risk of clinically significant hypokalemia, sometimes with severe muscle weakness, paralysis, rhabdomyolysis, or life-threatening arrhythmia.
Why is this important?
Case reports in the medical literature document hypokalemia, paralysis, hospital admission, and even cardiac arrest in patients who combined licorice with diuretics or who consumed large amounts of licorice on their own. Risk factors include older age, female sex, pre-existing hypertension, hypokalemia, and concurrent diuretic therapy - which describes a large fraction of furosemide users.
The catch is that licorice exposure can be hidden. People take licorice root extract for digestive complaints, sore throat, adrenal support, or peptic ulcer disease without recognizing it as a medicine. Glycyrrhizin is also a sweetener and flavoring agent in some teas, candies, herbal cough syrups, throat lozenges, and chewing tobacco. Just 100 mg of glycyrrhizin per day - which corresponds to about 50 grams of real licorice candy daily for two weeks - has been shown to cause pseudoaldosteronism in otherwise healthy adults.
Pseudoaldosteronism can take up to 6 months to fully resolve after stopping licorice, because glycyrrhetinic acid has a long elimination half-life. Recovery is the rule, but it is slow and unpleasant.
What should you do?
The simplest rule is to avoid licorice while you take furosemide.
- Skip licorice root tea, licorice tincture, licorice tablets, and adrenal-support blends that contain Glycyrrhiza glabra or G. uralensis.
- Read candy labels. Twizzlers and most U.S. "licorice" candy are flavored with anise oil and contain no glycyrrhizin. Authentic European licorice, Dutch drop, and salted licorice almost always contain real glycyrrhizin.
- Check herbal cough syrups, throat sprays, and lozenges - many contain licorice extract as a demulcent.
- If you need licorice for gastrointestinal use, choose deglycyrrhizinated licorice (DGL), which has had the glycyrrhizin removed and does not cause pseudoaldosteronism. Brands include Enzymatic Therapy DGL, Natural Factors DGL, and Rhizinate.
- Tell every prescriber and pharmacist about licorice use. The same warning applies to thiazide diuretics, corticosteroids, and digoxin.
- Symptoms of trouble include increasing leg swelling despite the same furosemide dose, rising blood pressure, muscle weakness or cramps, fatigue, and palpitations. Seek care promptly if these appear.
Which specific products are affected?
The interaction applies to any licorice product containing glycyrrhizin: licorice root teas (Yogi Egyptian Licorice, Traditional Medicinals Organic Licorice Root), bulk licorice root from herbal apothecaries, Chinese herbal formulas containing gan cao, traditional Japanese kampo formulas, throat coat blends, and adrenal-support supplements. Long-term consumption of authentic licorice candy and certain chewing tobaccos has caused the same syndrome.
Deglycyrrhizinated licorice (DGL) chewables and capsules are not affected, because the glycyrrhizin has been removed.
On the diuretic side, the interaction is most pronounced with loop diuretics (furosemide, torsemide, bumetanide) and thiazides (hydrochlorothiazide, chlorthalidone). Potassium-sparing diuretics such as spironolactone, eplerenone, amiloride, and triamterene partially blunt the effect by blocking the mineralocorticoid receptor or distal potassium secretion.
The bottom line
Licorice and furosemide both push potassium into the urine through different mechanisms. Combining them raises the risk of severe hypokalemia, worsening edema, and dangerous arrhythmias. Avoid glycyrrhizin-containing licorice products entirely while on furosemide; if you need licorice for gut health, use DGL.