In today's Health Matters, some treats this Halloween may trick you in a bad way.

The US Food and Drug Administration has a health warning about black licorice. Officials say people over 40 need to be careful about having to much of it.

The FDA says eating more than two ounces of it a day, every day for two weeks, can cause potassium levels to significantly drop.

It's all because of a sweetening compound in the candy derived from licorice root called Glycyrrhizin.

In high doses it can lead to an abnormal heartbeat, high blood pressure, water retention and swelling.