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Real-life vampires? People who are allergic to the sun

Bill Briggs writes:

Let’s start by driving a stake into the heart of some olds myths. People with sun allergies aren't really restless creatures of the night. They are not undead – although they may feel that way after, say, watching a marathon of the sun-drenched bikinifest “The Hills.”

While sunbeams don’t turn their skin sparkly like the vampire characters in "Twilight," one brief exposure to solar rays may send them screaming back to their dark places or, at least, to the doctor’s office.

Who are these people who dread the daylight? Chances are you know one.

American Academy of Dermatology
Bumpy rash caused by sun allergy

By some estimates, 45 million Americans – most of them northerners – are so hypersensitive to ultraviolet light that the first splash of spring sun causes itchy, red rashes or patches of small, red bumps to flare on uncovered areas of their chests, backs, upper arms, bellies or shoulders. They have a common condition called polymorphic light eruption (PLE), found in about 10 to 15 percent of people in North America.

There's another more rare condition linked to sun sensitivity called porphyria, sometimes known as "the vampire disease." Porphyria is an incurable, inherited disorder that affects the nervous system and skin. Symptoms include burning blisters and swelling of the skin when exposed to the sun, along with severe cramping, paralysis, and sometimes psychosis. Some historians blame porphyria for the madness of King George III. It's also often a favorite disease of TV shows, making an appearance in "House," "Scrubs" and, most recently, ABC's "Castle," where a character diagnosed with porphyria believes he's a vampire and sleeps in a coffin.

Vampires and TV plotlines aside, polymorphic light eruption is by far the most common type of sun allergy. Despite the "Twilight"-esque creepiness of its name, the disorder is generally harmless. PLE typically vanishes on its own in a few hours or a few days.

To soothe a PLE rash, a doctor may prescribe a topical cortisone cream or an oral steroid like prednisone. After an initial exposure to the warmer, intense beams of spring, PLE often goes dormant again for a year. Doctors says PLE does not seem to make one more susceptible to skin cancer. 

“It’s more common in fair-skinned people, but it can happen in any race,” said Dr. Susan M. Rabizadeh, a dermatologist with the Cedars-Sinai Medical Group in Los Angeles. “There is probably some genetic susceptibility – it can run in families. It’s sort of like an allergy. We see a fair amount of it because it is so prevalent.”

PLE is more common in women, especially younger women – who just happen to be the main lovers of popular romantic vampire fantasies.

Has the confluence of pop-sensation and skin-popping sun rash evoked any “Twilight” chatter among Dr. Rabizadeh’s patients?

“You mean, that they might be vampires? No,” Rabizadeh said with a laugh. “No, it hasn’t come up.”

But there are some mysteries about PLE that researchers enjoy sinking their teeth into.

The disorder seems to appear more frequently in people from higher northern (or higher southern) latitudes and less often in those who reside in more tropical climates. In Australia, for example, only about 5 percent of residents show PLE symptoms. It’s likely that people who live near the equator become slowly desensitized to the allergy-like condition through daily exposure to harsher UV rays. For patients who develop only mild PLE breakouts each spring, Rabizadeh said she encourages them “to just get a little sun exposure – protected with sunscreen – every day so that they can build a tolerance to it.” Doctors call that process “hardening.”

For a small number, PLE causes blistery rashes that are much more severe, longer-lasting and spread over larger areas of the body. For those patients, the prescription usually involves low doses of a special band of ultraviolet light called UVB (which induces vitamin D production in the skin) and a plant extract called psoralen (which helps absorb UV rays).

“Both are done at the doctor’s office. They take the plant extract an hour before they get narrow-band UVB light treatment,” Rabizadeh said. “Those patients receive the treatments three times a week for however many weeks it takes to get their reactions to go away – anywhere from a month to three to four months.”

Although lengthy, the regimen of fake light and plant extract is typically needed only once a year – in the spring, just as the days begin to grow longer.