Licorice and Blood Pressure Medications: What You Need to Know

Licorice and Blood Pressure Medications: What You Need to Know

Many people enjoy licorice candy or sip licorice tea thinking it’s just a sweet, harmless treat. But if you’re taking medication for high blood pressure, that piece of black licorice could be quietly undoing your treatment. The problem isn’t the flavor-it’s glycyrrhizin, the active compound in real licorice root. This substance doesn’t just add sweetness; it interferes with how your body handles salt, water, and potassium, directly clashing with the drugs designed to lower your blood pressure.

How Licorice Attacks Your Blood Pressure Control

Glycyrrhizin breaks down in your gut into glycyrrhetic acid, which blocks an enzyme in your kidneys called 11β-HSD2. Normally, this enzyme keeps cortisol-the stress hormone-from acting like aldosterone, a hormone that tells your body to hold onto salt and water and flush out potassium. When 11β-HSD2 is shut down, cortisol takes over. Your kidneys start behaving as if you’re flooded with aldosterone: sodium builds up, water follows, and potassium drains away.

This isn’t theoretical. Studies show that people who regularly consume more than 100 mg of glycyrrhizin a day-roughly 60 to 70 grams of traditional black licorice candy-see their systolic blood pressure rise by an average of 5.5 mmHg. That might not sound like much, but for someone already struggling to keep their blood pressure under control, it’s enough to push them into dangerous territory. Add in low potassium levels, which drop by 0.5 to 1.0 mmol/L in chronic users, and you’ve created the perfect storm for heart rhythm problems and muscle weakness.

Which Blood Pressure Medications Are Most Affected?

Licorice doesn’t play favorites-it undermines nearly every class of blood pressure medication. But some interactions are especially dangerous.

  • Diuretics (like hydrochlorothiazide or furosemide): These drugs help lower blood pressure by flushing out extra fluid. But they also make you lose potassium. Licorice does the same thing. Together, they can crash your potassium levels so low that your muscles go limp or your heart starts beating erratically.
  • ACE inhibitors (like lisinopril or captopril): These drugs relax blood vessels and reduce fluid buildup. Licorice does the opposite-it adds fluid. The result? Your medication stops working, and your blood pressure climbs.
  • Calcium channel blockers (like amlodipine or nifedipine): While these aren’t directly affected by the same enzyme, the extra fluid volume from licorice makes them less effective at lowering pressure.
  • Digoxin (Lanoxin): This one is life-threatening. Low potassium from licorice lets digoxin bind too tightly to heart cells. That can cause nausea, confusion, visual disturbances, and even fatal heart rhythms. There are documented cases of older adults ending up in the hospital with heart failure after taking herbal laxatives that contained licorice.
  • Potassium-sparing diuretics (like spironolactone or eplerenone): These are meant to keep potassium up. But licorice forces it out anyway. You’re essentially fighting yourself.

It doesn’t matter if you take your meds exactly as prescribed. If you’re eating licorice daily, your treatment is compromised.

What Counts as ‘Licorice’? Not All of It Is the Same

Not every candy labeled ‘licorice’ contains glycyrrhizin. In fact, most modern black licorice candies in North America and Europe are flavored with anise oil and contain no real licorice root at all. The problem is, you can’t tell by looking. A red licorice twist? Probably safe. A dark, chewy stick? Could be loaded with glycyrrhizin.

Real licorice root is found in:

  • Traditional black licorice candy (especially imported or artisanal brands)
  • Licorice root tea and herbal infusions
  • Dietary supplements labeled as ‘licorice root extract’ or ‘Glycyrrhiza glabra’
  • Some cough syrups and throat lozenges
  • Traditional herbal remedies for digestion or adrenal support

Always check the ingredient list. If it says ‘licorice root,’ ‘glycyrrhizin,’ or ‘Glycyrrhiza glabra,’ you’re at risk. If it just says ‘natural flavoring’ or ‘anise,’ you’re likely safe.

Kitchen counter with licorice root tea affecting a kidney, while anise flavor is harmless, elderly person checks blood pressure.

Who’s at the Highest Risk?

Not everyone reacts the same way. Some people can eat a small piece of licorice once in a while with no issues. But certain groups are far more vulnerable:

  • People over 60: Aging kidneys are less able to handle the extra salt load.
  • Women: Studies show women are more sensitive to glycyrrhizin’s effects, possibly due to hormonal differences.
  • Those with existing high blood pressure: Your body is already working hard to keep pressure down. Licorice adds resistance.
  • People with heart failure or kidney disease: Your fluid balance is already fragile. Adding salt and water can trigger sudden worsening.
  • Anyone taking digoxin: Even small amounts of licorice can tip you into toxicity.

If you fall into one of these categories, the safest move is to avoid licorice entirely.

Signs You Might Be Having a Reaction

Many people don’t realize they’re reacting to licorice until symptoms become severe. Watch for:

  • Unexplained rise in blood pressure, even while taking meds
  • Muscle weakness, cramps, or a feeling of heaviness in limbs
  • Fatigue or lethargy that doesn’t go away
  • Swelling in ankles or legs (edema)
  • Irregular heartbeat, palpitations, or dizziness
  • Headaches or blurred vision

These symptoms often appear after just two to four weeks of daily consumption. If you notice any of these, stop eating licorice immediately and get your potassium and blood pressure checked. A simple blood test can reveal if your cortisol-to-cortisone ratio is off-a clear sign that glycyrrhizin is interfering with your body’s hormone balance.

Doctor shows low potassium blood test as a licorice-tangled heart beats irregularly in a hospital room.

What Should You Do?

If you’re on blood pressure medication:

  1. Stop eating black licorice candy unless you’re certain it’s glycyrrhizin-free.
  2. Check supplement labels. Avoid anything with ‘licorice root’ or ‘Glycyrrhiza glabra.’
  3. Ask your pharmacist if any of your current supplements contain licorice.
  4. Monitor your blood pressure at home. If it starts rising without explanation, consider licorice as a possible cause.
  5. Get a blood test if you’re feeling weak or your BP won’t budge. Low potassium is a red flag.

There’s no need to panic if you’ve had licorice once or twice. But if you’ve been eating it daily-even just a few pieces a week-it’s time to cut it out. Your blood pressure meds will work better without it.

What About Licorice for Health Benefits?

You might have heard licorice is good for digestion, sore throats, or adrenal fatigue. Some studies suggest glycyrrhizin has anti-inflammatory properties. But the risks far outweigh the benefits-especially if you’re on blood pressure meds. There are safer alternatives for all of these issues: ginger for digestion, honey and lemon for sore throats, and stress-reduction techniques for adrenal support. Don’t trade your heart health for a myth.

Even ‘deglycyrrhizinated licorice’ (DGL), sold as a supplement for ulcers, removes glycyrrhizin intentionally. If you want licorice flavor without the risk, choose DGL products-but only after confirming they’re truly glycyrrhizin-free.

The Bottom Line

Licorice isn’t just a sweet snack. For people on blood pressure medication, it’s a hidden threat. It doesn’t just reduce your meds’ effectiveness-it can make you sicker. The science is clear: over 100 mg of glycyrrhizin per day causes measurable harm. Many people don’t realize they’re consuming it daily through candy, tea, or supplements.

If you’re taking medication for high blood pressure, the safest choice is to avoid real licorice completely. Read labels. Ask questions. Don’t assume a candy is safe just because it’s labeled ‘licorice.’ And if you’ve been eating it regularly and your blood pressure won’t go down, stop-and get checked. Your heart will thank you.

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