Margaritas may be the choice cocktail on July 24 to celebrate National Tequila Day, but Dr. Howard Steinman, a dermatologist with DermOne Dermatology Centers, has a sour warning: Sipping citrus fruit beverages in the sun can lead to phytophotodermatitis, marked by skin discoloration and sometimes blistering.

Phytophotodermatitis, or "Lime Disease" as it is sometimes popularly called, is an inflammation of the skin caused by a chemical reaction between photosensitizing compounds found in certain plants and foods – especially limes – and exposure to sunlight. Results can be a red, sometimes blistering, skin eruption that often causes strangely-shaped streaks and can even look like a sunburn.  The rash can then turn dark brown which can last for months if not treated.

Dr. Steinman explains, “It is common to see cases of lime-causing rashes during the summer season. I’ve seen cases of skin discoloration on wrists, face, neck and chests from tequila shots, where the drinkers squeezed limes while outside, and the juice dribbled on their skin.  It is also seen in children and adults who pick fresh limes and then make lime juice. Because this is a reaction from the lime juice coming in contact with the skin during sun exposure, it can often leave unique patterns unlike rashes or a typical sunburn.”

The best prevention is not to cut or squeeze limes while making or drinking margaritas and other lime-ingredient beverages in the sun. Immediately washing hands and body parts that had direct contact with the limes can also prevent the rash.  Sunscreen is not a preventative solution for this "Lime Disease" although proper usage of sunscreen is always encouraged to help prevent skin cancer. 

Treatment of the initial rash is with cortisone-based creams and antihistamine medications.  The brown discoloration can be treated with sun protection, fading creams and camouflage make-up.