Yes, licorice can harm your kidneys, but the risk depends on how much you consume and how often. The active compound in licorice, glycyrrhizic acid, triggers a chain reaction in your body that raises blood pressure, depletes potassium, and forces your kidneys to work harder. For most people, an occasional piece of black licorice candy poses no real threat. Regular or heavy consumption is where the problems start.
How Licorice Affects Your Kidneys
Your kidneys have a built-in protective system. An enzyme normally prevents the stress hormone cortisol from activating receptors that control sodium and potassium balance. Glycyrrhizic acid, the main bioactive compound in licorice root, blocks that enzyme. When cortisol floods those unprotected receptors, your body starts behaving as though you have extremely high levels of aldosterone, the hormone that tells your kidneys to hold onto sodium and dump potassium.
This condition is called pseudoaldosteronism. It mimics the effects of excess aldosterone, but actual aldosterone and renin levels in your blood are suppressed, sometimes to nearly undetectable levels. The result is a trio of problems: high blood pressure, dangerously low potassium, and fluid retention. Your kidneys are both the site of the disruption and one of the organs most affected by it.
What Happens When Potassium Drops Too Low
Normal potassium levels sit between 3.5 and 5.0 mmol/L. In documented cases of licorice toxicity, potassium has fallen as low as 1.6 mmol/L, a level that can cause life-threatening heart rhythm problems. In one published case, a patient’s potassium sat stubbornly between 2.3 and 2.6 mmol/L for days despite aggressive supplementation, only improving after a potassium-sparing medication was added on day five. Blood pressure in that patient peaked at 189/91 mmHg.
When potassium plunges this low, muscles can break down, releasing a protein called myoglobin into the bloodstream. That protein is filtered through the kidneys, and in large amounts it can clog the kidney’s filtration system and trigger acute kidney failure. This is one of the most serious, though less common, complications of excessive licorice intake.
How Much Licorice Is Too Much
The World Health Organization sets a recommended upper limit of 2 mg of glycyrrhizic acid per kilogram of body weight per day. For someone weighing 70 kg (about 154 pounds), that ceiling is 140 mg daily. Here’s what that looks like in real products:
- A pack of Liquorice Allsorts: about 91 mg of glycyrrhizic acid
- A cup of licorice tea: roughly 20 mg per serving
- A single licorice pipe candy: about 4.6 mg
The concentration of glycyrrhizic acid varies enormously between products, ranging from 0.26 to 7.9 mg per gram. Herbal supplements tend to sit at the higher end of that range. A meta-analysis of 18 studies found that the average daily dose causing health effects was about 378 mg of glycyrrhizic acid, equivalent to roughly 189 grams (about 6.7 ounces) of black licorice candy per day. But some individuals, particularly older adults and those with existing kidney or heart conditions, develop problems at lower amounts.
People With Kidney Disease Face Higher Risk
If you already have chronic kidney disease, licorice is especially risky. Your kidneys are already less efficient at balancing sodium, potassium, and fluid levels. Adding a compound that actively disrupts those systems can push you into dangerous territory faster and at lower doses than someone with healthy kidneys.
Mayo Clinic includes black licorice on its list of substances to avoid when you have kidney disease. That warning covers not just licorice root supplements and candy but also beverages and foods with black licorice flavoring. If you take diuretics or blood pressure medications, licorice can compound the potassium-lowering effects of those drugs.
Recovery After Stopping Licorice
The good news is that the damage is usually reversible once you stop consuming licorice. Potassium levels can normalize within a few days. In one case, a patient’s potassium returned to 3.7 mmol/L and blood pressure dropped to 121/73 mmHg just three days after stopping licorice and receiving treatment.
The underlying enzyme disruption takes longer to resolve. The protective enzyme that licorice blocks can remain suppressed for about two weeks after you stop, and the broader hormonal effects on the renin-aldosterone system can linger for several months. One patient who had consumed 60 to 100 grams of licorice daily for four to five years showed suppressed renin and aldosterone levels for nearly four months after quitting. In the case series involving an elderly patient, once the effects fully cleared, blood pressure stabilized enough that the patient no longer needed blood pressure medication at all.
Deglycyrrhizinated Licorice as a Safer Option
If you enjoy licorice for its flavor or use it for digestive comfort, deglycyrrhizinated licorice (DGL) removes the problem compound. Manufacturing processes can strip out up to 97% of glycyrrhizic acid, dropping the content from about 83 micrograms per milligram of extract down to roughly 2.5 micrograms. DGL supplements are widely available and have been used for years to soothe stomach and duodenal ulcers without the blood pressure and potassium side effects.
Interestingly, laboratory research suggests that the other compounds in licorice, not glycyrrhizic acid, may actually have protective effects on kidney cells. In studies on kidney cells exposed to high glucose (a model for diabetic kidney disease), deglycyrrhizinated licorice extract reduced harmful cellular changes associated with kidney scarring. The glycyrrhizic acid itself showed only weak activity against those changes, even at high concentrations. So the compound causing kidney harm may not be the one providing licorice’s other potential benefits.
Signs of Licorice-Related Kidney Stress
Symptoms of licorice toxicity tend to build gradually if you’re a regular consumer. Watch for persistent headaches, swelling in your ankles or hands, muscle weakness or cramping, and fatigue. These reflect the rising blood pressure, fluid retention, and falling potassium that precede more serious complications. Heart palpitations or an irregular heartbeat are warning signs that potassium has dropped to a concerning level. If you consume black licorice regularly and notice any combination of these symptoms, stopping licorice and getting your potassium and blood pressure checked is the straightforward next step.