Yes, black licorice can be bad for your heart. The compound that gives it its distinctive flavor, glycyrrhizin, lowers potassium levels in your body, which can trigger dangerous irregular heart rhythms. The FDA warns that people over 40 who eat more than two ounces a day for two weeks or longer may be at risk for arrhythmia serious enough to require hospitalization.
How Black Licorice Affects Your Heart
The problem starts in your kidneys. Your body naturally produces cortisol, a hormone that can activate receptors controlling sodium and potassium balance. Normally, an enzyme in your kidneys deactivates cortisol before it can overstimulate those receptors. Glycyrrhizin, the sweetening compound in licorice root, blocks that enzyme. With the brake removed, cortisol floods in and flips on a system that was meant to stay quiet.
The result is a cascade: your kidneys hold onto more sodium and water while flushing out potassium. Blood pressure climbs. Potassium drops. And potassium is essential for the electrical signals that keep your heart beating in a steady rhythm. When levels fall low enough, those signals misfire, producing irregular heartbeats known as arrhythmias. In one published case, a patient’s potassium dropped to 1.7 mEq/L, less than half the normal minimum, after excessive licorice consumption. That level is low enough to cause muscle paralysis and life-threatening heart rhythm disturbances.
Blood Pressure and Potassium: A Double Hit
Licorice doesn’t just affect heart rhythm. It raises blood pressure through the same mechanism. The sodium and water retention that comes with potassium loss increases blood volume, pushing pressure higher. In one documented case, a patient’s blood pressure peaked at 177/98 mmHg during hospitalization for licorice toxicity, then dropped to 128/86 after she stopped eating it. This pattern, high blood pressure paired with low potassium and suppressed levels of the hormones that normally regulate both, is characteristic enough that doctors call it “pseudohyperaldosteronism.” Your body looks like it’s producing too much aldosterone (the hormone that controls sodium and potassium), but it isn’t. Licorice is mimicking the effect.
How Much Is Too Much
The FDA’s threshold is specific: for people 40 and older, eating more than two ounces of black licorice daily for at least two weeks can be enough to cause problems. Two ounces is roughly five or six pieces, depending on the brand. That said, sensitivity varies. People with existing heart conditions, high blood pressure, or low potassium are more vulnerable at lower amounts.
Occasional indulgence is a different story. A few pieces of black licorice at a party or a handful around Halloween is unlikely to cause trouble for most people. The risk comes from regular, sustained consumption, the kind of habit where someone works through a bag every day or two.
Who Faces the Greatest Risk
Age matters. The FDA specifically flags people over 40 as higher risk, likely because cardiovascular reserves are thinner and blood pressure is already trending upward for many people in that age range. But medication use may be an even bigger factor. If you take diuretics (water pills), you’re already losing potassium through your urine. Adding licorice on top of that accelerates the depletion. The same goes for anyone taking medications that affect potassium balance or mineralocorticoid activity. The combination can push potassium dangerously low faster than either one would alone.
People with pre-existing heart rhythm disorders, heart failure, or kidney disease should be particularly cautious, since their bodies are less able to tolerate the shifts in electrolytes and fluid balance that licorice triggers.
Red Licorice Is Not the Same
Red licorice contains no licorice root and no glycyrrhizin. It’s flavored with fruit extracts and other sweeteners. The American Heart Association has noted that red licorice and artificially flavored black licorice carry no heart risk from glycyrrhizin, since neither contains it. The danger is specific to products made with real licorice root. Check the ingredients list: if glycyrrhizin or licorice extract appears, the product carries the same risk as traditional black licorice. This also applies to licorice root teas, supplements, and chewing tobacco that uses licorice flavoring from the actual root.
What Recovery Looks Like
The good news is that licorice’s effects are reversible once you stop eating it. Muscle weakness, if present, can improve within days once potassium is restored. Blood pressure and potassium levels generally return to normal within several weeks. However, the hormonal system that regulates sodium and potassium balance (the renin-aldosterone system) can take months to fully reset. During that recovery window, blood pressure and electrolytes may still be somewhat unstable, which is why monitoring matters even after symptoms improve.