At first glance, black licorice seems like just another nostalgic candy—rich, sweet, and deeply flavored. But beneath its seemingly innocent exterior lies a lesser-known risk that can turn a beloved treat into a health hazard. The story took a tragic turn in 2020, when a 54-year-old man in Massachusetts died after consuming an excessive amount of black licorice. How could a candy lead to such a severe outcome? The answer lies in the science behind this unique confection.
The Toxicology of Licorice: Dose Matters
As Paracelsus, the father of toxicology, famously said, “The dose makes the poison.” Black licorice contains a compound called glycyrrhizin (also known as glycyrrhizic acid), extracted from the root of the licorice plant (Glycyrrhiza glabra). This chemical gives black licorice its signature sweet, slightly bitter flavor—and also its potential for harm.
When consumed in large amounts over time, glycyrrhizin can disrupt the delicate balance of electrolytes in the body, particularly sodium and potassium. This imbalance arises because glycyrrhizin mimics aldosterone, a hormone that regulates sodium retention and potassium excretion. Too much glycyrrhizin causes the body to hold onto sodium while losing potassium, leading to high blood pressure, irregular heart rhythms, muscle pain, headaches, and swelling. In the Massachusetts case, the man had been eating about a bag and a half of black licorice daily for three weeks, resulting in dangerously low potassium levels and ultimately fatal complications.
Who Is at Risk?
While occasional indulgence in black licorice is unlikely to cause harm, certain groups are more vulnerable. People over 40 who consume large quantities of black licorice regularly face the greatest risk. Those with preexisting conditions such as hypertension, low potassium, heart arrhythmias, or liver and kidney issues are especially sensitive, as their bodies may not effectively clear glycyrrhizin, allowing it to build up to toxic levels.
Complicating matters, glycyrrhizin hides in more than just candy. It is also used in some beverages (like certain teas and Belgian beers), throat lozenges, and even tobacco products. Supplements that contain licorice can add to the total daily intake, increasing the danger unknowingly.
Moreover, some medications—particularly diuretics like hydrochlorothiazide—can deplete potassium levels, compounding the effects of glycyrrhizin and raising the risk of serious heart and muscle problems.
Not All Licorice Is Created Equal
It’s important to distinguish real licorice from impostors. Many red licorice products, popular in candy stores, do not contain any licorice extract but use artificial flavors such as cherry or strawberry. Similarly, some “black licorice” flavored candies rely on anise oil—a flavoring that mimics licorice but does not carry the same risks associated with glycyrrhizin.
If you want to avoid the dangers of glycyrrhizin, check the ingredient list for “licorice extract” or “glycyrrhizic acid.” Products like black jelly beans or Good & Plenty often contain both licorice extract and anise oil, so moderation is key.
How Much Is Too Much?
According to the U.S. Food and Drug Administration (FDA), eating more than 2 ounces of black licorice daily for two weeks or longer can lead to serious health problems, especially in people over 40. A recent study from Sweden echoed this warning, showing that consuming 100 mg of licorice daily for just two weeks raised participants’ blood pressure and strained their hearts, even at relatively low doses.
For healthy adults and children, enjoying black licorice occasionally in small amounts is generally safe. However, it’s wise to treat it as an occasional treat—not a daily snack—and to monitor any symptoms such as muscle weakness, irregular heartbeat, or swelling.
Should You Avoid Licorice Supplements and Teas?
Some use licorice root supplements or teas to address coughs, sore throats, or even respiratory infections like COVID-19. Yet scientific reviews caution against the routine use of licorice in supplements due to the risk of chronic side effects. The benefits tend to be minor compared to the potential for harm, particularly when consumed regularly over long periods.
Final Thoughts: Enjoy Licorice Responsibly
Black licorice is a flavorful confection with a long history of use as a traditional remedy. But its key chemical, glycyrrhizin, can upset your body’s electrolyte balance and cardiovascular health when consumed excessively. To enjoy licorice safely:
- Limit your intake to small amounts occasionally.
- Avoid eating large quantities daily, especially for extended periods.
- Check labels to identify products containing real licorice extract.
- Be cautious if you have preexisting health conditions or take medications affecting potassium levels.
- Consult your healthcare provider if you experience symptoms like irregular heartbeat or muscle cramps after eating licorice.
By respecting the old adage that “the dose makes the poison,” you can appreciate black licorice for what it is—a sweet treat with a complex chemistry best enjoyed in moderation.
About the Author
Bill Sullivan, Ph.D., is a toxicologist and author dedicated to exploring how chemicals in our environment and food impact health. He teaches at the Indiana University School of Medicine and authored Pleased to Meet Me: Genes, Germs, and the Curious Forces That Make Us Who We Are.