Too much Halloween candy really can make you sick, especially if you’ve got a fondness for licorice, according to the Food and Drug Administration.

As ghosts and goblins prepare for trick-or-treating, the FDA is warning adults that eating too much of the old-fashioned favorite could land them in the hospital.

Eating 2 ounces of black licorice a day for at least two weeks could cause an irregular heart rhythm or arrhythmia in adults over 40, the agency says. That’s because the candy contains glycyrrhizin, which can cause potassium levels in the body to fall. When that happens, some people experience abnormal heart rhythms, as well as high blood pressure, edema (swelling), lethargy, and congestive heart failure.

The FDA said doctors report that potassium levels are usually restored when the patient stops eating black licorice.

Here are 13 other tips to keep you safe this Halloween, courtesy of FDA, the Consumer Product Safety Commission and the U.S. Centers for Disease Control and Prevention:

Safe Costumes

1. Wear costumes made of fire-retardant materials; look for “flame resistant” on the label. If you make your costume, use flame-resistant fabrics such as polyester or nylon.

2. Wear bright, reflective costumes or add strips of reflective tape so you’ll be more visible; make sure the costumes aren’t so long that you’re in danger of tripping.

3. Wear makeup and hats rather than masks that can obscure your vision.

4. Test the makeup you plan to use by putting a small amount on the arm of the person who will be wearing it a couple of days in advance. If a rash, redness, swelling, or other signs of irritation develop where the makeup was applied, that’s a sign of a possible allergy.

5. Check FDA’s list of color additives to see if makeup additives are FDA approved. If they aren’t approved for their intended use, don’t use it.

6. Don’t wear decorative contact lenses unless you have seen an eye care professional and gotten a proper lens fitting and instructions for using the lenses.

Safe Treats

7. Don’t eat candy until it has been inspected at home.

8. Trick-or-treaters should eat a snack before heading out, so they won’t be tempted to nibble on treats that haven’t been inspected.

9. Tell children not to accept — or eat — anything that isn’t commercially wrapped.

10. Parents of very young children should remove any choking hazards such as gum, peanuts, hard candies, or small toys.

11. Inspect commercially wrapped treats for signs of tampering, such as an unusual appearance or discoloration, tiny pinholes, or tears in wrappers. Throw away anything that looks suspicious.

Safe Parties

12. Look for the warning label to avoid juice that hasn’t been pasteurized or otherwise processed, especially packaged juice products that may have been made on site. When in doubt, ask! Always ask if you are unsure if a juice product is pasteurized or not. Normally, the juice found in your grocer’s frozen food case, refrigerated section, or on the shelf in boxes, bottles, or cans is pasteurized.

13. Before bobbing for apples — a favorite Halloween game — reduce the amount of bacteria that might be on apples by thoroughly rinsing them under cool running water. As an added precaution, use a produce brush to remove surface dirt.