What happens when you take licorice tea with digoxin?
This combination is a problem not because the two react with each other directly, but because licorice quietly changes your body chemistry in a way that makes digoxin more powerful. Here is the chain of events:
- Licorice blocks a kidney enzyme. Licorice root (Glycyrrhiza glabra) contains glycyrrhizin, which the body converts to glycyrrhetinic acid. This compound inhibits a kidney enzyme called 11-beta-hydroxysteroid dehydrogenase type 2, whose normal job is to switch off cortisol in cells that respond to the salt-regulating hormone aldosterone.
- The body acts as if it has too much salt hormone. With that enzyme blocked, cortisol activates the mineralocorticoid receptor as if it were aldosterone. This produces a state called apparent mineralocorticoid excess: the body holds onto sodium and water, blood pressure can rise, and potassium is flushed out in the urine.
- Potassium falls, often silently. With regular licorice intake, blood potassium can drop gradually over days to weeks. Many people feel nothing until potassium is already low.
- Low potassium makes digoxin stronger. Digoxin works by binding the sodium-potassium pump on heart cells. Potassium competes for that same binding site, so when potassium falls, more of the pump is available for digoxin to bind. The same digoxin dose now has a greater effect on the heart, edging toward toxic territory.
Published case reports describe patients developing digoxin toxicity after licorice-induced potassium loss, which is why this pair is treated as a serious interaction rather than a theoretical one.
Why is this important?
Digoxin has one of the narrowest safety margins of any common medication: the dose that helps the heart and the dose that harms it are not far apart. A modest drop in potassium can be enough to shift a previously stable patient toward toxicity, without any change to the prescription.
Digoxin toxicity is not a minor event. It can cause dangerous heart rhythm disturbances, including extra beats, abnormal fast rhythms, and severe slowing or blocking of the heartbeat. Other warning signs include nausea, vomiting, loss of appetite, fatigue, confusion, and a characteristic disturbance of vision such as yellow or green halos around lights. Sometimes a serious arrhythmia is the first sign, with no nausea or visual warning beforehand.
The amount of licorice needed to lower potassium is smaller than many people expect, and it does not require a supplement: a regular habit of strong licorice tea or real black licorice candy can be enough in susceptible people. Older adults, women, people of low body weight, and anyone with kidney problems lose potassium more readily and are at higher risk.
What should you do?
If you take digoxin, treat licorice as something to avoid rather than something to merely limit. The safest approach is to plan around it:
Before any change: Tell your clinician and pharmacist about every herbal tea, candy, and supplement you use, and check the labels on digestive teas, "throat coat" style blends, herbal cough products, and traditional Chinese herbal formulas, which often contain licorice root (sometimes listed as gan cao). Do not start a licorice-containing product without confirming it is safe with your digoxin.
Every day: Keep your digoxin routine and your usual diet steady, and skip licorice tea and real black licorice. Consistency matters because digoxin's effect depends on a stable potassium level.
After any change or concern: If you have already been consuming licorice, stop it and contact your clinician promptly. Ask whether you should have your potassium, magnesium, and digoxin level checked; the potassium-losing effect can persist for a while after you stop, so recovery is not instant. Seek urgent care for new palpitations, an irregular or very slow pulse, severe fatigue or confusion, persistent nausea or vomiting, or visual changes such as halos around lights.
One important exception: the interaction does not apply to deglycyrrhizinated licorice (DGL), a form used for reflux and gastritis from which the glycyrrhizin has been removed. If you use a licorice product for digestion, confirm with a pharmacist that it is genuinely deglycyrrhizinated.
Which specific products are affected?
On the medication side, this concern centers on digoxin (sold as Lanoxin and Digox) and the related cardiac glycoside digitoxin. Because the underlying problem is potassium loss, the same licorice effect can also add risk for people taking diuretics, certain heart-rhythm drugs, and other medications that are sensitive to low potassium; your pharmacist can review your full list.
On the licorice side, the products to watch include licorice root tea, throat coat and digestive herbal tea blends, real black licorice candy (such as Dutch drop, Australian licorice, and European Panda or Halva-style licorice), licorice extracts and lozenges, herbal cough syrups containing licorice, licorice spice blends, and traditional Chinese herbal formulas containing gan cao.
A couple of common look-alikes do not carry this risk: Twizzlers and similar U.S. "licorice" candies usually contain no real licorice, and star anise tea is sometimes confused with licorice but does not contain glycyrrhizin. Deglycyrrhizinated licorice (DGL) is also exempt.
The science behind it
The mechanism and the clinical concern are both well documented. A review in Therapeutic Advances in Endocrinology and Metabolism (Omar et al., 2012) summarizes how glycyrrhizin causes potassium loss through the mineralocorticoid pathway and explicitly describes a patient who developed digoxin toxicity from licorice-induced hypokalemia, alongside the broader rhythm risk that low potassium creates.
The underlying biology is reinforced by case reports of licorice-induced pseudohyperaldosteronism (for example, a 2025 report in Clinical Case Reports), which trace the path from glycyrrhizin to enzyme inhibition to hypokalemia. Standard drug-interaction references likewise classify digoxin combined with licorice as a major interaction, on the basis that potassium and magnesium depletion makes the heart muscle more sensitive to digoxin. This is a recognized, mechanism-based interaction documented mainly through case reports rather than large trials, which is consistent with how electrolyte-driven digoxin toxicity is studied.
Frequently Asked Questions
Is an occasional cup of licorice tea dangerous if I take digoxin?
The risk comes mainly from regular, repeated intake that lowers potassium over time, rather than a single cup. Still, because digoxin's safety margin is so narrow, the prudent approach is to avoid licorice tea altogether and ask your clinician about your own situation.
What symptoms should make me seek help right away?
New palpitations, an irregular or very slow pulse, severe fatigue or confusion, persistent nausea or vomiting, or visual changes such as yellow or green halos around lights all warrant urgent medical attention while on digoxin.
Is deglycyrrhizinated licorice (DGL) safe with digoxin?
DGL has the glycyrrhizin removed, so it does not cause the potassium loss that drives this interaction. If you use a licorice product for digestion, confirm with a pharmacist that it is truly deglycyrrhizinated.
Does this affect candy as well as tea?
Yes. Real black licorice candy contains the same glycyrrhizin as the tea. Note that many U.S. candies labeled "licorice" (such as Twizzlers) contain no real licorice, while European, Dutch, and Australian black licorice typically do.
How long does it take for potassium to recover after stopping licorice?
The potassium-losing effect can persist for some time after you stop, so recovery is gradual rather than immediate. Your clinician can decide whether and when to recheck your levels.
Could licorice affect other heart medications too?
Because the problem is low potassium, licorice can add risk for several medications sensitive to electrolyte levels, including some diuretics and heart-rhythm drugs. Ask your pharmacist to review your full medication list.
Key takeaways
- Licorice can lower potassium, and low potassium makes digoxin more potent and more likely to become toxic.
- Digoxin has a very narrow safety margin, so even modest potassium changes matter.
- If you take digoxin, avoid licorice tea and real black licorice; check labels on herbal teas, cough products, and Chinese herbal formulas.
- If you have been consuming licorice, stop and contact your clinician about checking potassium and digoxin levels; seek urgent care for palpitations, an irregular or very slow pulse, nausea, confusion, or visual changes.
- Deglycyrrhizinated licorice (DGL) does not carry this risk.