Licorice root interacts with a surprisingly wide range of medications, including common blood pressure drugs, diuretics, heart medications, blood thinners, corticosteroids, and hormonal contraceptives. The active compound responsible, glycyrrhizic acid, mimics the effects of a hormone that raises blood pressure and depletes potassium. That combination can amplify the risks of many drugs or cancel out the benefits of others.
These interactions apply to real licorice root, licorice extract, and licorice-flavored products that contain actual glycyrrhizin. They do not apply to most licorice-flavored candy in the U.S., which typically uses anise flavoring instead. The distinction matters, and we’ll cover it at the end.
How Licorice Affects Your Body
Understanding why licorice clashes with so many drugs starts with what it does inside your body. Your kidneys have an enzyme that normally deactivates cortisol (a stress hormone) before it can trigger salt and water retention. Glycyrrhizic acid in licorice blocks that enzyme. The result: cortisol floods receptors it normally wouldn’t reach, and your body starts behaving as though you have far too much aldosterone, the hormone that tells your kidneys to hold onto sodium and excrete potassium.
This creates a condition called pseudohyperaldosteronism. Your blood pressure rises, your potassium drops, and your body retains extra fluid. On its own, that’s a problem. Layered on top of certain medications, it becomes dangerous.
Blood Pressure Medications
Licorice directly undermines the goal of every blood pressure drug. ACE inhibitors, calcium channel blockers, and beta-blockers all work to bring blood pressure down, while licorice pushes it up through sodium and water retention. The result isn’t a subtle tug-of-war. Licorice can make these medications appear to stop working entirely, leading to poorly controlled hypertension that may prompt unnecessary dose increases or medication changes.
If you’re taking any antihypertensive and your blood pressure is creeping up despite treatment, regular licorice consumption is worth flagging to your prescriber.
Diuretics (Water Pills)
This is one of the most clinically significant interactions. Thiazide diuretics like hydrochlorothiazide already lower potassium as a side effect. Licorice does the same thing through a different mechanism. Together, potassium can drop fast. In one study of healthy volunteers, combining even low-dose licorice with hydrochlorothiazide caused 20% of participants to become hypokalemic, and both affected subjects hit dangerously low levels within the first week, requiring early discontinuation.
Loop diuretics carry similar risks. Any medication designed to increase urine output and shed sodium will compound licorice’s potassium-depleting effects, potentially causing muscle weakness, cramping, heart rhythm disturbances, or worse.
Digoxin and Other Heart Medications
Digoxin, used for heart failure and certain arrhythmias, has a narrow margin between a therapeutic dose and a toxic one. What determines whether a normal dose becomes toxic isn’t just the drug level in your blood. It’s your potassium level. When potassium drops, the heart muscle becomes far more sensitive to digoxin’s effects. Toxicity can occur even when blood levels of the drug appear completely normal.
Licorice’s ability to deplete both potassium and magnesium makes it a serious risk factor for digoxin toxicity, which can cause nausea, visual disturbances, and life-threatening arrhythmias.
Warfarin and Blood Thinners
Licorice interacts with warfarin through multiple pathways at once. Compounds in licorice extract inhibit the liver enzymes (in the P450 system) that break down warfarin, causing the drug to accumulate to higher-than-expected levels. On top of that, glycyrrhizin independently prolongs clotting times, and another licorice-derived compound has antiplatelet activity. These effects stack.
In one documented case, an 80-year-old woman on warfarin ate a pound of black licorice on two separate occasions. Her INR, a measure of how thin the blood is, shot from a baseline of 2.1 to 5.5, and her red blood cell count dropped from 34 to 14, indicating severe internal bleeding. After she stopped eating licorice, her INR returned to normal within two weeks. While a pound of licorice is an extreme amount, the case illustrates how dramatically the interaction can escalate.
Corticosteroids
If you take prednisone, prednisolone, or hydrocortisone, licorice can amplify their effects in ways your prescriber didn’t account for. Glycyrrhizin slows the liver’s breakdown of prednisolone, raising both the peak concentration and the total drug exposure over time. In pharmacokinetic terms, the drug stays in your system longer and at higher levels than expected.
This means all the side effects of corticosteroids, including fluid retention, high blood sugar, mood changes, and bone thinning, become more likely. The interaction is especially concerning for people on long-term steroid therapy, where even small increases in effective dose compound over weeks and months.
Oral Contraceptives and Hormone Therapy
Estrogen-containing birth control pills already carry a small risk of raising blood pressure. Prolonged licorice use appears to amplify this effect while also lowering potassium. For most people on hormonal contraceptives, occasional licorice exposure is unlikely to cause problems. But regular consumption, particularly in the form of licorice root tea, supplements, or European-style licorice candy, adds an unnecessary cardiovascular burden on top of a medication that already slightly elevates that risk.
How Much Licorice Is Dangerous?
There’s no universally agreed-upon safe threshold, but the effects are dose-dependent. Most documented cases of pseudohyperaldosteronism involve consuming more than about one ounce (30 grams) of real licorice per day over several weeks. That said, sensitivity varies widely. Some people develop high blood pressure and low potassium from smaller amounts, particularly older adults and those already on medications that affect potassium or blood pressure.
The risk is cumulative. Glycyrrhizic acid doesn’t leave the body quickly, so daily consumption matters more than a single indulgence.
DGL Licorice Is the Exception
Deglycyrrhizinated licorice, sold as DGL, has had the glycyrrhizin removed. This is the compound responsible for virtually all the drug interactions listed above. DGL supplements, commonly used for digestive comfort, do not carry the same interaction risks. If you take any of the medications mentioned here and want the flavor or digestive benefits of licorice, DGL is the form to look for. Check the label: it should explicitly state “deglycyrrhizinated” or “DGL.”
Where Licorice Hides
Real glycyrrhizin shows up in places you might not expect. European and Middle Eastern licorice candy typically contains actual licorice root. So do many herbal teas (especially “throat coat” or digestive blends), some chewing tobaccos, certain traditional Chinese medicine formulations, and licorice root supplements. Most American “licorice” candy, like Red Vines or Twizzlers, uses anise oil for flavor and contains no glycyrrhizin at all.
If you’re on any of the medications above, the key habit is reading ingredient labels. Look for “licorice root,” “licorice extract,” or “glycyrrhizin.” If it’s there, treat it as a potential interaction.