Ever heard of “lime disease”? Prevention has nothing to do with ticks

Employees from Tinhat Creative have an office party at Papagayo restaurant in Boston, MA  (Yoon S. Byun/Globe Staff)
Employees from Tinhat Creative have an office party at Papagayo restaurant in Boston, MA (Yoon S. Byun/Globe Staff)

As a health reporter, I’m pretty well versed in common medical problems, but I’d never heard about “lime disease”—not to be confused with Lyme disease—until reading this post on everyday health. It’s a painful, itchy rash that sometimes causes blisters and appears a day or two after skin splattered with lime juice sits under the sun.

Dermatologists refer to it by its scientific name, phytophotodermatitis, but perhaps “bartender disease” is the most fitting moniker since it’s likely to plague those mixing margaritas on sunny outdoor patios, said Dr. Joe Merola, a dermatologist at Brigham and Women’s Hospital.

Fruits, vegetables, or plants that contain compounds called psoralens—limes, celery, parsnip, parsley, certain wild carrots, and figs—increase the skin’s sensitivity to sunlight. This can lead to blistering rashes if the plant juices get on the skin before sun exposure.

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“It’s an allergic reaction but if you put enough lime juice on any skin, there will be a reaction to the sun,” said Merola who treats a handful of cases each summer. “It’s kind of like poison ivy.”

The rash tends to have an unnatural-looking shape, he added, due to how the juice was distributed on the arm. It may be in the shape of a hand print or a thin line where the juice ran down the arm. People who handle limes or are avid gardeners of root vegetables should wear gloves when outdoors to protect their skin or wash their hands and arms before heading into the sunlight.

If a rash appears, the irritated area should be washed with soap and water.

“You can treat it with an over-the-counter topical steroid like hydrocortisone,” Merola said.

Dermatologists can prescribe stronger prescription creams if that doesn’t bring relief.

The rash usually clears in a few days, but a brownish pigment may remain on the skin for weeks afterward.

A host of chemicals in products ranging from skin creams to shampoos can cause photoallergic reactions, especially those with fragrances, Merola said. If you have any unexplained blistery rashes this summer, a dermatologist can perform photo patch testing—where they put tiny doses of a dozen or more chemicals on the skin before exposing the areas to sunlight.