NEW YORK (Reuters) - In a TV advertisement for Corona beer, a woman on a beach, irritated by her companion ogling a bikini-clad blonde, squirts him with the lime sitting atop his beer.
He may be in for worse than a surprise: a nasty skin reaction that one doctor is calling "Mexican beer dermatitis."
A substance in lime juice, if left on the skin in the sun, can cause the skin to become discolored, as if by poison ivy or a jellyfish sting -- and the marks can last for months, reports Scott Flugman in the Archives of Dermatology.
Mexican beers, particularly Corona, are typically served with a lime slice wedged in the top of the bottle. The drinker shoves the lime into the bottle and holds his or her thumb over the bottle's mouth while turning the bottle over to mix in the juice.
But if the drinker is not careful, the beer's carbonation can spray lime juice and beer all over his or her skin -- "especially in a patient who is shirtless by a beach or pool," wrote Flugman, a dermatologist in New York.
The resulting reaction is due to a substance called psoralen, used to make the skin more sensitive to a wavelength of ultraviolet light, UV-A, used to treat certain skin conditions.
Lemons contain psoralens too, but not as strong.
"It's just a cosmetic issue," Flugman told Reuters Health, though he said the discoloration -- most frequently in people like bartenders who work outdoors with limes -- may take an emotional toll.
"People are worried that it's something serious. You might have some brown spots you're been looking at for a few months," he said. Olive-skinned Caucasians may be especially susceptible.
No ties have been shown between the reaction and skin cancer, said Flugman, who added that he sees two or three cases a year.
They are often mystified why a dermatologist is asking them if they've recently drunk Mexican beer.
"If you do this and you spritz the beer or the lime, just wash it off. Don't leave it on there and sit out in the sun," he said.
Or, if you are disinclined to get up for a while, "throw a towel over it."
Reporting by Ivan Oransky at Reuters Health; editing by Elaine Lies and Ron Popeski