Nothing beats a summer day with a margarita in hand and sand between your toes. But spill some of that margarita while lying out in the sun, and you could end up with a nasty chemical burn like this one:

Eek! Just looking at that makes us hurt. Lime juice is usually the culprit for the reaction, known as phytophotodermatitis but often cheekily referred to as "lime disease" (not to be confused with Lyme disease).

Limes—and other fruits and veggies, including carrots, celery, and lemons—contain furocoumarins, which cause skin damage (chemical burns and blisters) when exposed to UVA light, says A. Yasmine Kirkorian, M.D., a dermatologist at the George Washington University School of Medicine and Health Sciences.

Unfortunately there isn't research that shows how many limes (or lemons) you can squeeze before you should be worried. “I suspect that casual contact with limes or other fruits—one or two squeezes—is less likely to result in phytophotodermatitis than squeezing a huge batch of limes," Kirkorian says. "But the exact amount of contact that will result in a rash is unknown.”

This is one of those cases where it's better to be safe than sorry. Lucky for us citrus lovers, these bizarre burns are relatively easy to prevent. The best defense: Wash your hands really well with soap and water after handling the fruit. Lathering on sunscreen can also help, since it protects your skin from UVA rays.

We know getting out of your beach chair to wash off a spilled margarita might put a dent in your perfect summer day, but the potential alternative (see below) just isn't worth it.

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