Chances are you’re going to get a wide assortment of candy and treats on Halloween, but you should avoid one in particular, warns the U.S. Food and Drug Administration. While all candy is certainly not very good for you, black licorice in particular can be extremely bad for your heart.

THe reason is that it contains something called glycyrrhizin, which can cause a drop in potassium levels in your body, which further leads to abnormal heart rhythems, high blood pressure, and even heart failure in extreme cases. As they say, moderation is key, so if you’re just eating a little bit it’s probably not a big deal, but more than 2 ounces of black licorice a day for at least two weeks in those who are more than 40 years old greatly increases your risk.

Of course, black licorice is far from the most popular Halloween treat, so it’s not a particularly big risk. But it’s still something you should be aware of. And don’t forget, gorging on candy isn’t going to be good for your heart, no matter what kind it is.

“As it turns out, you really can overdose on candy—or, more precisely, black licorice,” the FDA says. “Days before the biggest candy eating holiday of the year, the Food and Drug Administration (FDA) encourages moderation if you enjoy snacking on the old fashioned favorite So, if you’re getting your stash ready for Halloween, here’s some advice from FDA: If you’re 40 or older, eating 2 ounces of black licorice a day for at least two weeks could land you in the hospital with an irregular heart rhythm or arrhythmia.”