Man suffers chemical burn that lasted months after squeezing limes

If Margaritaville were a real place, it should definitely keep a few dermatologists on hand.

In a case of an oft-overlooked food preparation risk, a 40-year-old man showed up to an allergy clinic in Texas with a severe, burning rash on both his hands that had two days earlier. A couple of days later, it blistered. And a few weeks after that, the skin darkened and scaled. After several months, the skin on his hands finally returned to normal.

The culprit: lime juice and sunlight.

It turns out that just before developing the nasty skin eruption, the man had manually squeezed a dozen limes, then headed to an outdoor soccer game without applying sunscreen. His doctors diagnosed the man’s rash as a classic case of phytophotodermatitis, according to a case report published Wednesday in the New England Journal of Medicine.

The condition is caused by toxic substances found in plants (phyto) that react with UV light (photo) to cause a burning, blistering, scaling, pigmented skin condition (dermatitis).

Specifically, the toxic chemicals are furocoumarins, which are found in some weeds and also a range of plants used in food. Those include celery, carrot, parsley, fennel, parsnip, lime, bitter orange, lemon, grapefruit, and sweet orange. Furocoumarins include chemicals with linear structures, psoralens, and angular structures, called angelicins, though not all of them are toxic.