Lime Juice and Sunshine Can Make for Painful, Unexpected Sunburn - Health Essentials from Cleveland Clinic

Next time you're sipping margaritas on the patio, be extra careful when squeezing that fresh lime into your drink. The parts of your skin that have been exposed to both the fruit and the sun may be susceptible to phytophotodermatitis, a form of extreme sunburn.

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What does this mouthful of a term mean? Here's a breakdown:

• Phyto means "plant."
• Photo means "light" or "sun."
• Dermatitis means "skin rash."

Phytophotodermatitis, then, is the skin's exaggerated response to the sun, resulting in light-to-severe blistering that may look like sun poisoning or a rash.

Why it happens

Dermatologist Melissa Piliang, MD explains that some plants and fruits — especially citrus fruits — contain furocoumarins, an organic chemical compound that can make skin more sensitive to the sun and worsen the effects of sunburn.

"Typically phytophotodermatitis is a topical reaction, where you've spilled something on yourself," she says, "but it can also happen from eating celery soup, as celery contains furocoumarins."

Foods that can lead to phytophotodermatitis include:

• Buttercups.
• Carrots.
• Celery.
• Citrus fruits (especially limes and bergamot oranges).
• Fennel.
• Figs.
• Hogweed.
• Pelea anisata (often used in Hawaiian leis).
• Saint John's Wort.
• Wild dill.
• Wild parsley.
• Wild parsnips.

"I commonly see phytophotodermatitis when somebody has been barbecuing on a sunny afternoon and having drinks with limes in them, like margaritas or beers with a lime squeezed in," Dr. Piliang says. "Anything where they're cutting and squeezing limes and splashing the juice on themselves and then enjoying the sunshine."

Dr. Piliang says once, a patient had a poison ivy-like rash on the top of her forearms after mowing the lawn. Turns out, she'd been making guacamole beforehand, and some of the lime had gotten onto her skin before she headed outdoors.

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Phytophotodermatitis is sometimes called "margarita burn," for obvious reasons. A subset is known as "berloque dermatitis," a 1920s reference to the fact that it frequently affected people who wore perfumes and colognes containing bergamot oil, which is derived from furocoumarin-containing oranges.

Who it afflicts

Fair-skinned folks and those who are typically sensitive to the sun are at higher risk for phytophotodermatitis, while individuals with darker skin don't usually see such reactivity.

Hospitality industry, beware: Chefs, bartenders, and others who work with food may be more likely to be exposed to foods containing furocoumarins, especially when serving on patios, working at pool bars, and the like.

And because plenty of wild plants contain furocoumarins, hikers, bikers, and other outdoorsy types may also be more vulnerable to exposure.

How to identify it

Because phytophotodermatitis occurs where skin has come into contact with toxins from plants and fruit, it can be difficult to identify — and may show up in strange formations, like streaks, splotches, or even handprints.

The signs of phytophotodermatitis might not kick in immediately after you've been in the sun. In 24 to 48 hours, your skin might start to feel tingly and tender and begin to redden. Within another day or two, painful blisters will develop in the affected areas.

Once the blisters heal, they typically leave behind brown hyperpigmentation in the affected areas of the skin. Though painless, those spots can take months to fade — and they're likely to darken if re-exposed to sunlight.

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What to do about it

A mild case of phytophotodermatitis might go largely unnoticed, while other people's reactions are severe enough to send them to the doctor for help. "It all depends on how much of a dose of the fruit or plant you got on your skin and how long you were in sun," Dr. Piliang says.

Here's what to do if you suspect you have phytophotodermatitis:

• Keep the affected area clean and use cold, wet compresses as needed for the pain.
• Apply a topical antibiotic ointment and bandage the affected area, taking special care to keep it covered and out of the sun.
• Tempting though it may be, definitely don't pop those blisters.

"If you have widespread blisters, blisters on your hands or face, or if the blisters are inhibiting your ability to use your hands, it's time to see somebody," Dr. Piliang says. Head to a dermatologist for a prescription topical steroid that can reduce inflammation and lessen the pain.

Once your blisters have healed, leaving hyperpigmentation behind, be sure to keep those spots out of the sun, too. Keep them covered with bandages, sleeves or sun-protected clothing to promote faster fading.

How to prevent it

Good news for people who are susceptible to phytophotodermatitis: Once you know the risks, it's relatively easy to prevent them.

If you're using citrus fruits and other furocoumarin-heavy ingredients in food prep, whether outside or soon to be heading into the sun, be sure to thoroughly wash your hands and arms with soap and water. And if you're headed into a woodsy area, wear long pants to cover areas that could come into contact with wild flora.

"It is important to be aware that this can happen, and practice safe sun behaviors," Dr. Piliang advises. That includes staying out of the sun when possible and always wearing sunscreen — as you're hopefully doing anyway.