Updated 10/27/2023
I’ll be honest, I’m not a fan of black licorice…or anything that tastes remotely like it. But there are plenty of people who do! So it’s important that they are aware of the food-drug interaction that can occur with some medications as they can be very dangerous.
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What compound in licorice is responsible for this interaction?
Glycyrrhizin (pronounced glis-eer-eye-zin) is acompound found primarily in natural black licorice. You likely won’t find this ingredient in its red counterpart because it’s what gives black licorice its flavor. However, most black licorice sold in the U.S. in candy form contains anise oil which smells and tastes similar. Anise oil will not interact with these medications and is a safer option.
Which medications interact with black licorice?
Digoxin/Lanoxin – Glycyrrhizin can cause a drop in potassium levels while retaining sodium in the body. When potassium levels are depleted, the medication digoxin, used to treat heart failure, is enhanced causing an irregular heart beat.
Coumadin/Wafarin – The interaction between this blood thinner medication and glycyrrhizin can cause an increase in the body’s blood clotting mechanism which can be fatal if not treated.
Water pills (Lasix, Edecrin, Diuril, etc) – When you consume natural black licorice in large quantities, your blood potassium levels can drop. Taking these diuretics (water pills) also decreases potassium levels in the blood. That means combining the diuretic and licorice can cause potassium levels in the blood to drop to unsafe levels.
How to find glycyrrhizin in foods
If you find licorice extract in the ingredient list, the product will also contain glycyrrhizin. This is not the only food this compound can be found in though. You’ll likely see it in various herbal teas. Brands such as Yogi and Stash use licorice root as the first ingredient in some of their teas.
For those who like the taste, you can consume the artificially flavored black licorice (such as the Twizzlers brand) which doesn’t contain this ingredient and is therefore safe with these medications.
One more thing…
Even if you aren’t taking these medications, it’s important to limit how much you consume at one time. If you have high blood pressure, heart disease, or diabetes, consuming too much can cause muscle weakness, numbness in limbs, and increased blood pressure.
Want to know more about other food-drug interactions? Check out my other blog posts:
Tyramine and MAOIs
Grapefruit