Eating too much real black licorice can cause dangerously low potassium levels, high blood pressure, and in extreme cases, cardiac arrest. These aren’t theoretical risks. A case published in The New England Journal of Medicine described a man who died of cardiac arrest after eating a bag and a half of black licorice daily for several weeks. The culprit is a natural compound called glycyrrhizin, found in licorice root, that disrupts how your body handles sodium and potassium.
How Licorice Disrupts Your Body’s Chemistry
Your kidneys have a built-in system to keep the hormone cortisol from activating receptors meant for aldosterone, a hormone that controls your salt and water balance. An enzyme acts as a gatekeeper, converting cortisol into an inactive form before it can reach those receptors. Glycyrrhizin blocks that enzyme. When it does, cortisol floods in and mimics aldosterone, telling your kidneys to hold onto sodium and dump potassium.
The result is a condition doctors call pseudoaldosteronism: your body acts as if it’s producing massive amounts of aldosterone even though it isn’t. Sodium builds up, potassium drops, and blood pressure rises. What makes this particularly tricky is that the effects can linger for weeks after you stop eating licorice, because glycyrrhizin doesn’t just temporarily block the enzyme. With chronic use, it may actually suppress the enzyme’s production, meaning your body needs time to rebuild its defenses.
The Symptoms to Recognize
Licorice toxicity typically shows up as a triad: severely low potassium, high blood pressure, and a shift in blood chemistry called metabolic alkalosis. In one documented case, a patient’s potassium dropped to 2.3 mmol/L, well below the normal range of 3.5 to 5.0. Their blood pH climbed to 7.54, far more alkaline than the body prefers.
What you’d actually feel depends on severity. Mild cases might cause constipation, muscle weakness, or cramps. More serious potassium depletion can trigger palpitations, numbness or tingling in the extremities, and abdominal discomfort. At its worst, critically low potassium destabilizes the heart’s electrical rhythm. A study at a single medical center identified six patients who needed intensive care for licorice toxicity between 2018 and 2020, and all of them presented with the same pattern of high blood pressure, low potassium, and metabolic alkalosis.
Not All Licorice Is Dangerous
This only applies to products containing real licorice root extract. Red licorice candy contains no glycyrrhizin at all. And even some black licorice candies use artificial flavors or anise oil (which tastes similar) instead of the real thing. As one cardiologist put it to the American Heart Association, black licorice with artificial flavor and red licorice are “identically not dangerous.”
The risk comes from products that list licorice extract, licorice root, or glycyrrhiza glabra in their ingredients. Beyond candy, glycyrrhizin shows up in certain herbal teas, some root beers, and licorice root supplements. If you’re a regular consumer of any of these, check the label.
Who Faces the Highest Risk
Older adults are especially vulnerable. The case studies involving hospitalization and intensive care disproportionately involve elderly patients, whose kidneys and cardiovascular systems have less margin for error. People with existing heart conditions or high blood pressure face compounded risk, since their bodies are already working harder to maintain electrolyte balance.
Pregnant women should be particularly cautious. A Finnish study that followed 378 children born in 1998 found that mothers who consumed high amounts of glycyrrhizin during pregnancy (500 mg or more per week) had children with measurable differences at age 12. Girls were taller, heavier, and showed more advanced pubertal development. Both boys and girls scored about 7 points lower on IQ tests, performed worse on memory assessments, and had 3.3 times the odds of attention deficit/hyperactivity problems compared to children whose mothers consumed little or none. The likely mechanism is the same enzyme disruption: glycyrrhizin blocks the placental barrier that normally protects the fetus from the mother’s cortisol.
Dangerous Combinations With Medications
Licorice becomes especially risky when paired with medications that also lower potassium. Diuretics (water pills) are the most common culprit. If you’re already losing potassium through a diuretic and then adding licorice-driven potassium loss on top of it, you can reach dangerous levels faster than either would cause alone.
The combination with digoxin, a heart medication, is particularly hazardous. Digoxin’s toxicity is directly related to potassium levels. When potassium drops, digoxin becomes more potent and more dangerous at the same dose. At least one documented case involved digoxin toxicity triggered specifically by licorice-induced potassium depletion. Anyone taking heart medications, blood pressure drugs, or diuretics should treat real licorice products as a genuine drug interaction, not just a dietary preference.
How Much Is Too Much
There’s no perfectly defined safe threshold, which is part of the problem. Individual sensitivity varies widely based on age, kidney function, and other medications. The FDA has warned that eating 2 ounces of black licorice daily for two weeks can cause heart rhythm problems in people over 40. The lethal case involved roughly a bag and a half per day over several weeks, but serious toxicity has been reported at lower amounts, especially with sustained daily consumption.
The practical takeaway: occasional black licorice is fine for most people. Daily, habitual consumption of products containing real licorice extract is where the danger zone begins, and the risk scales with both quantity and duration. If you notice muscle weakness, unusual fatigue, or heart palpitations and you’ve been eating black licorice regularly, stopping is the obvious first step, but be aware that symptoms can take several weeks to fully resolve even after you quit.