Licorice and Medications: Unexpected Interactions with a Common Candy

Most people think of licorice as just a sweet, chewy candy-something you grab at the checkout counter or share with kids during a movie night. But if you’re taking any kind of medication, that little black stick might be doing more than satisfying a craving. It could be quietly messing with your blood pressure, draining your potassium, or even undoing the effects of your prescriptions. And you probably have no idea.

What’s Really in Licorice?

Not all licorice is the same. The real stuff comes from the root of the licorice plant (Glycyrrhiza glabra), and its main active ingredient is glycyrrhizin. This compound is what gives licorice its distinctive flavor-and its powerful, sometimes dangerous, effects on your body. Traditional black licorice candy can contain anywhere from 0.5% to 2% glycyrrhizin. That means a single 50-gram bag might have 100 to 200 milligrams of it. And if you’re eating a few bags a week? You’re hitting the upper limit of what’s considered safe.

Here’s the catch: many products labeled "licorice" aren’t real licorice at all. In the U.S. and elsewhere, anise oil is often used to mimic the flavor because it’s cheaper and doesn’t carry the same risks. So if you’re eating red licorice, or even some black varieties, you might be fine. But if you’re buying "real licorice" from a health food store, herbal supplement, or imported candy-especially from Europe-you could be consuming far more glycyrrhizin than you realize. Labels rarely say how much.

How Licorice Changes Your Body

Glycyrrhizin acts like a fake version of aldosterone, a hormone your kidneys use to control salt and water balance. When it binds to receptors in your kidneys, your body starts holding onto sodium and flushing out potassium. That sounds harmless, until you realize what that does to your blood pressure and heart.

Low potassium (hypokalemia) can cause muscle cramps, fatigue, and irregular heartbeat. Sodium retention leads to fluid buildup-swollen ankles, weight gain, and high blood pressure. In one documented case, a 47-year-old man ate 200 grams of licorice daily for three weeks. His blood pressure shot up to 210/120. His potassium dropped to 2.6 mmol/L (normal is 3.5-5.0). He needed hospitalization.

This isn’t rare. Between 2010 and 2020, the FDA recorded 147 adverse events linked to licorice. Over 40% involved high blood pressure. Nearly 30% involved dangerously low potassium. And these are just the cases that got reported.

Medications That Get Dangerous When Mixed With Licorice

If you’re on any of these medications, licorice isn’t just a snack-it’s a risk.

• Diuretics (like hydrochlorothiazide or furosemide): These drugs help you pee out extra fluid, but they also lower potassium. Licorice does the same. Together, they can drop potassium to life-threatening levels. One patient on a water pill developed potassium levels below 3.0 mmol/L after eating licorice daily.
• Antihypertensives (like lisinopril or losartan): These are meant to lower blood pressure. Licorice raises it. A Reddit user reported his BP jumped from 120/80 to 165/95 in just three days after eating 30 grams of licorice daily while on lisinopril.
• Fludrocortisone: This steroid mimics aldosterone. Adding licorice to it is like pouring gasoline on a fire. One man developed panic attacks and blood pressure over 200/110 after eating licorice while already taking this drug.
• Warfarin and other blood thinners: Licorice can either make warfarin work too well (raising bleeding risk) or reduce its effect, increasing clot risk. One woman on phenprocoumon saw her INR drop suddenly after eating licorice-enough to trigger a stroke warning.
• Digoxin: Used for heart rhythm problems. Low potassium makes digoxin toxic. A 2002 case showed a patient developed digoxin toxicity after licorice consumption, with potassium at 2.8 mmol/L.
• Metformin: Animal studies suggest licorice may reduce its effectiveness. Human data is still limited, but it’s enough to warrant caution in people with diabetes.

And here’s the twist: some licorice compounds can speed up how your liver breaks down drugs, while others slow it down. So even if your medication isn’t directly affected by potassium or blood pressure, licorice might still alter how much of it stays in your system. That’s why Memorial Sloan Kettering warns that licorice could interfere with drugs like cyclosporine, tacrolimus, and even some antidepressants.

Who’s at Risk?

You don’t have to be a licorice addict to be in danger. The European Food Safety Authority says healthy adults should not exceed 100 mg of glycyrrhizin per day-about two 50-gram bars of strong black licorice. But if you’re over 60, have high blood pressure, heart disease, kidney problems, or are pregnant, you’re far more sensitive. Even a small amount can cause problems within days.

And here’s something most people don’t know: the effects don’t go away right away. Glycyrrhizin sticks around in your body for days after you stop eating it. So if you had a few pieces last week and now your BP is spiking, it might not be coincidence.

What About Deglycyrrhizinated Licorice (DGL)?

DGL is a version of licorice with most of the glycyrrhizin removed. It’s often sold for digestive issues like heartburn or ulcers. If you’re on medications and want the taste or digestive benefits of licorice, DGL is your safest bet. It contains less than 1% glycyrrhizin-far below the danger threshold. Just make sure the label says "deglycyrrhizinated" clearly. Don’t assume.

What Should You Do?

If you’re on medication and you like licorice, here’s what to do:

1. Check the label. If it doesn’t say "real licorice" or "glycyrrhizin content," assume it’s risky. Anise-flavored candy is safe.
2. Limit intake. If you eat real licorice, don’t go over 100 mg glycyrrhizin per day-and even that’s pushing it if you’re on meds.
3. Monitor your body. Watch for swelling, headaches, muscle weakness, or sudden changes in blood pressure or heart rhythm.
4. Talk to your doctor or pharmacist. Most don’t ask about candy. But if you tell them you eat licorice regularly, they can check your potassium and blood pressure and adjust meds if needed.
5. Switch to DGL if you want licorice flavor without the risk.

A 2021 study found only 37% of community pharmacists could correctly identify all major licorice-drug interactions. That means you might be the only one who knows what you’re eating-and what it could be doing to your meds.

The Bigger Picture

The global licorice market is worth over $1.3 billion, with supplements and candies driving most of the growth. Yet 78% of black licorice products don’t disclose glycyrrhizin content. Nearly all of them skip warning labels. In the UK, labeling is required if a product contains more than 100 mg per serving. In the U.S.? No such rule. Japan limits supplements to 100 mg/day. Europe is considering reclassifying high-glycyrrhizin licorice as a medicine, not food.

Meanwhile, research continues. A 2025 review identified a new metabolic pathway linking licorice to water retention. Clinical trials are now testing whether your genes (like CYP2C9 or CYP2D6 variants) affect how you respond to glycyrrhizin. That means someday, your DNA might tell you whether licorice is safe for you.

For now, though, the message is simple: if you’re taking any kind of medication, especially for blood pressure, heart, or kidney issues, treat licorice like a drug-not a snack.

Next time you reach for that bag of black licorice, ask yourself: Is this a treat-or a hidden risk? When it comes to your medications, it’s better to be safe than sorry.