Licorice Root and Blood Pressure Medications: Why It Makes Them Work Less

Have you ever taken licorice root as a supplement, sipped licorice tea, or munched on black licorice candy while on blood pressure medication-and then noticed your numbers creeping up? You’re not imagining it. Licorice root can seriously weaken the effect of your blood pressure pills, sometimes within days. And most people have no idea.

How Licorice Root Sneaks Into Your System

Licorice root comes from the plant Glycyrrhiza glabra. It’s been used for centuries in traditional medicine for coughs, stomach issues, and inflammation. But its sweet taste hides a dangerous side effect: a compound called glycyrrhizin. This is what turns licorice from a harmless herb into a silent saboteur of your blood pressure treatment.

Glycyrrhizin doesn’t just sit there. Once you consume it, your body breaks it down into glycyrrhetic acid, which blocks a key enzyme called 11β-hydroxysteroid dehydrogenase type 2. Normally, this enzyme keeps cortisol (a stress hormone) from acting like aldosterone (a hormone that makes your body hold onto salt and water). When glycyrrhetic acid shuts it down, cortisol takes over. Result? Your kidneys start reabsorbing sodium like crazy, flushing out potassium, and holding onto extra fluid. That’s a recipe for high blood pressure.

What Happens When You Mix It With Your Meds

If you’re taking blood pressure medication, this fluid buildup directly fights against what your pills are trying to do. Here’s how it messes with common drugs:

• ACE inhibitors (like lisinopril): Their ability to relax blood vessels drops by 30-50%. You might think your dose isn’t working-but it’s not the pill. It’s the licorice.
• ARBs (like losartan): Effectiveness falls by about 25%. Blood pressure climbs even when you take your pill on time.
• Calcium channel blockers (like amlodipine): Control gets 15-20% worse. Your heart and arteries aren’t getting the full benefit.
• Potassium-sparing diuretics (like spironolactone): This is the worst combo. Licorice can cancel out the entire effect in under two weeks. Your potassium plummets, your blood pressure spikes, and you could end up in the ER.

A 2015 study showed some people saw their systolic blood pressure jump by as much as 30 mmHg after just two weeks of daily licorice. That’s like going from 130 to 160-without changing anything else.

It’s Not Just Candy

Most people think they’re safe if they avoid candy. But licorice root hides in places you wouldn’t guess:

• Herbal teas labeled “licorice root” or “Glycyrrhiza glabra”
• Dietary supplements for digestion, adrenal support, or “natural energy”
• Cough syrups and throat lozenges
• Traditional Chinese medicine formulas (about 25% contain it)
• Some herbal laxatives (30% include licorice root)
• Even certain tobacco products

And here’s the kicker: 95% of licorice-flavored candies in the U.S. don’t even contain real licorice. They use anise oil instead. So if you’re eating red or salted licorice, you’re probably fine. But if you see “licorice extract” or “Glycyrrhiza glabra” on the label, you’re at risk.

How Much Is Too Much?

The European Food Safety Authority says 100 mg of glycyrrhizin per day is the upper safe limit for healthy adults. But if you’re on blood pressure meds? That’s not safe. Not even close.

One gram of raw licorice root can contain anywhere from 20 to 240 mg of glycyrrhizin. That means a single 20-gram piece of licorice candy could deliver up to 480 mg-nearly five times the “safe” amount. And because glycyrrhizin sticks around in your system for up to two weeks after you stop, even occasional use can cause trouble.

A 2020 case report described a patient whose blood pressure shot to 210/115 after just 10 days of licorice tea while on spironolactone. He needed hospitalization. His potassium level dropped to 2.8 mmol/L-dangerously low.

What You Should Do

If you’re on any blood pressure medication, here’s your action plan:

1. Check every label. Look for “Glycyrrhiza glabra,” “licorice root,” or “licorice extract.” Avoid anything with it.
2. Ask your pharmacist. They can check your supplements and even your cough syrup. Many don’t realize licorice is in them.
3. Switch to DGL. Deglycyrrhizinated licorice (DGL) has the beneficial compounds for digestion but removes over 99% of glycyrrhizin. It’s safe for people on blood pressure meds.
4. Get your potassium checked. If you’ve ever had licorice, ask your doctor for a blood test. Levels below 3.5 mmol/L mean trouble.
5. Track your blood pressure. If your numbers suddenly rise without reason, think about what you’ve added to your routine. Licorice is a top suspect.

Why Doctors Don’t Always Warn You

It’s not that doctors are ignoring this. It’s that most patients don’t tell them they’re taking licorice. In a 2021 survey, only 37% of supplement labels even mention the risk of high blood pressure. So if you’re reading “supports adrenal health” on a bottle and assume it’s harmless, you’re not alone.

But here’s the truth: over 150 case reports worldwide show people ending up in the hospital because of this interaction. And in 6 out of 8 documented cases, patients didn’t even know they were consuming real licorice. They thought they were just having tea or a cough drop.

What’s Changing

The U.S. FDA has issued warnings since 2017 but hasn’t forced labels to show glycyrrhizin content. The EU requires warning labels on products with more than 10 mg per serving. That’s why you’ll see “Not recommended for people with high blood pressure” on European licorice candy.

The FDA’s proposed Dietary Supplement Listing Act of 2023 could change that. If passed, manufacturers would have to list active ingredients-including glycyrrhizin-in plain language. That would make it a lot harder for people to accidentally overdose.

Until then, the burden is on you.

Bottom Line

Licorice root isn’t just a sweet treat. For anyone on blood pressure medication, it’s a hidden threat. It doesn’t just cause side effects-it actively makes your treatment fail. And it doesn’t take much. Two weeks of daily tea, candy, or supplement use can undo months of careful management.

The good news? You don’t need to give up all sweetness. Just avoid anything with real licorice root. Stick to anise-flavored candy. Choose DGL if you need digestive support. And always check labels. Your blood pressure-and your health-depend on it.