(CNN) – Too much black licorice this Halloween could come with some unwanted side effects.
The Food and Drug Administration warns it contains a sweetener called Glycyrrhizin that could cause a drop in potassium levels.
When that happens, some people experience abnormal heart rhythms, high blood pressure, and congestive heart failure.
The potassium levels usually get back to normal when people stop eating the black licorice, the FDA reports.
They also suggest that people who take regular medications or dietary supplements consult their healthcare provider before eating it.