Black licorice is a chewy candy flavored with extract from the root of the licorice plant (Glycyrrhiza glabra), a legume native to southern Europe and parts of Asia. What sets it apart from most candies is glycyrrhizin, a naturally occurring compound in licorice root that is 50 to 100 times sweeter than table sugar and gives black licorice its distinctive bittersweet, slightly medicinal taste. That same compound is also why black licorice carries real health risks that other sweets do not.
What’s Actually in It
Commercial black licorice starts with a base of wheat flour and sweeteners like corn syrup, similar to many other soft candies. The flavor comes from licorice root extract and, in most modern recipes, anise oil or star anise. All three of these sources share a compound called anethole, which produces the unmistakable “licorice” taste. Many manufacturers today rely more heavily on anise than on actual licorice root because anise is sweeter and less bitter. Still, any product labeled “black licorice” typically contains at least some real licorice extract, and with it, glycyrrhizin.
Glycyrrhizin is the compound that matters most, both for flavor and for health. It has a characteristic slow onset of sweetness and a lingering aftertaste, which is part of what makes black licorice so polarizing. People tend to love it or hate it, and that drawn-out sweetness is why.
Black Licorice vs. Red Licorice
Red licorice twists contain no licorice plant extract at all. They get their flavor from artificial or fruit-based flavorings and are called “licorice” only because they share the same rope-like shape and chewy texture. The American Licorice Company, which makes Red Vines, states plainly that only black licorice is truly licorice because it contains elements of the licorice plant. Red varieties carry none of the health concerns associated with glycyrrhizin.
Why Licorice Root Has Been Used for Centuries
Long before it became candy, licorice root was a medicinal herb. Traditional uses span digestive complaints (stomach ulcers, bloating, colic) and respiratory problems (coughs, sore throat, bronchial congestion). Glycyrrhizin appears to help with upper respiratory symptoms by promoting mucus secretion in the airways, which loosens congestion. In the digestive tract, compounds in licorice root have demonstrated antiulcer activity by suppressing gastric acid secretion.
Because glycyrrhizin causes side effects at higher doses, a modified form called deglycyrrhizinated licorice (DGL) was developed. DGL is licorice extract with the glycyrrhizin removed, and it’s sold as lozenges, capsules, and chewable wafers. It’s used by people who want the digestive benefits of licorice without the cardiovascular risks, and researchers at institutions like Memorial Sloan Kettering have noted that DGL is often preferred in studies precisely because it avoids glycyrrhizin’s adverse effects.
How Glycyrrhizin Affects Your Body
Glycyrrhizin interferes with an enzyme in the kidneys that normally keeps cortisol (a stress hormone) in check. When that enzyme is blocked, cortisol builds up and activates receptors that tell the kidneys to hold on to sodium and flush out potassium. The result mimics a condition called hyperaldosteronism: your body retains water, your blood pressure rises, and your potassium drops. Low potassium can cause muscle weakness, cramping, and in severe cases, dangerous heart rhythm disturbances.
A randomized crossover trial found that even a modest daily dose of glycyrrhizin (100 milligrams, roughly equivalent to a small serving of black licorice candy) raised systolic blood pressure by about 3 points and significantly suppressed the hormones that regulate sodium and potassium balance. The researchers concluded that licorice was “more potent than previously known,” with measurable blood pressure effects at amounts many people would consider casual snacking.
How Much Is Too Much
The FDA warns that if you are 40 or older, eating just 2 ounces of black licorice a day for two weeks or more could land you in the hospital with an irregular heartbeat. Two ounces is not a large amount. It’s roughly a handful of pieces, less than what many people might eat in a single sitting while watching a movie.
The risk scales with how much you eat and how long you keep eating it. Occasional small amounts are unlikely to cause problems for most healthy adults. But daily consumption, especially over weeks, allows glycyrrhizin to accumulate and steadily shift your electrolyte balance. People who already have high blood pressure, heart disease, or kidney problems are at greater risk because their bodies are less able to compensate for the potassium loss and sodium retention.
Potassium levels typically return to normal once you stop eating licorice, and the blood pressure effects reverse as well. But the recovery window depends on how depleted your potassium became. In published case reports, some patients required hospitalization and intravenous potassium replacement before their heart rhythm stabilized.
What to Watch For
The early signs of too much glycyrrhizin are easy to dismiss: muscle weakness, fatigue, swelling in the legs or ankles, and headaches. If potassium drops further, you might notice heart palpitations, numbness, or unusual thirst. These symptoms can develop gradually over days or weeks of regular consumption, which is part of what makes licorice toxicity tricky. People rarely connect their candy habit to what feels like a cardiac problem.
If you enjoy black licorice, keeping your intake occasional rather than daily is the simplest way to avoid trouble. For people who want the flavor without the glycyrrhizin, candies flavored exclusively with anise oil exist, and DGL supplements offer digestive benefits without affecting blood pressure or potassium. Reading the ingredient list matters here: if “licorice extract” or “licorice root” appears on the label, glycyrrhizin is present.