Do not eat large amounts of black licorice this Halloween— or ever, warns the Food and Drug Administration.

The candy, made from a shrub usually found in Greece, Turkey and Asia, contains a compound (glycyrrhizin) that can lower a person’s potassium levels, FDA experts say. So, eating too much could cause heart problems, high blood pressure, swelling and sluggishness, an FDA advisory reports.

Last year, the FDA heard of at least one case of black licorice causing health problems, according to the advisory.

Especially for those 40-years-old and older, eating two ounces of black licorice a day for at least two weeks could throw off heart rhythms.

FDA says no one, young or old, should eat big quantities of black licorice at a time and advises anyone who has an irregular heart rhythm or muscle weakness to stop eating the candy immediately. Pregnant women should also avoid eating black licorice, the National Center for Complementary and Integrative Health advises.

Black licorice could also mix dangerously with medications that reduce potassium levels such as diuretics, the NCCIH warns.

According to the FDA advisory:

FDA’s Linda Katz, M.D., says last year the agency received a report of a black licorice aficionado who had a problem after eating the candy. And several medical journals have linked black licorice to health problems in people over 40, some of whom had a history of heart disease and/or high blood pressure. Katz says potassium levels are usually restored with no permanent health problems when consumption of black licorice stops.

Licorice, or liquorice, is a low-growing shrub mostly grown for commercial use in Greece, Turkey, and Asia. The National Institutes of Health (NIH) says the plant’s root has a long history of use as a folk or traditional remedy in both Eastern and Western medicine. It has been used as a treatment for heartburn, stomach ulcers, bronchitis, sore throat, cough and some infections caused by viruses, such as hepatitis; however, NIH says there are insufficient data available to determine if licorice is effective in treating any medical condition.

No one is saying not to eat the candy, just pace yourself friends.

Ashley May, USA TODAY Network