WASHINGTON - If you've hit the pool, chances are you've experienced an unfortunate rite of summer: The sunburn.
Skin so swollen it hurts to bend. The heat that rises from reddened shoulders. The "ow, ow, ow" from the shower after you'd thought the pain had faded.
For all the creams that promise to soothe, there aren't many effective treatments for a sunburn. Dermatologists say the best bet is some of the same drugs that relieve a headache - the ibuprofen found in Motrin and Advil, or naproxen brands such as Aleve.
Scientists don't know exactly what causes this kind of touch-sensitive pain, but research is getting them closer to some answers.
British scientists found a clue in healthy people who volunteered to be sunburned for science. The scientists controlled the beams of ultraviolet light so that only a small patch of the volunteers' arms got a medium burn, just enough for a unique kind of testing.
One reason sunburns are so common is that, by the time you see pink and head indoors, more damage already is brewing. Unlike an immediate burn from, say, touching a hot stove, a sunburn's pain is delayed as the red darkens over the next 24 to 48 hours.
Researchers from Kings College London tracked how their volunteers' sunburned skin became more sensitive. At the peak of pain, they cut away a small bit of damaged skin to analyze all the biochemical changes inside - and found a protein that's responsible for triggering the cascade of pain and redness.
The protein summons inflammation-causing immune cells to the damaged spot as sunburned skin cells die off. Its activity increased more than did other pain-related chemicals as the sunburn worsened, the researchers reported last month in the journal Science Translational Medicine.
It took further experiments with rats to show that the molecule, named CXCL5, was a key culprit. Injecting rats' sunburned feet with a substance that tamped down the protein also tamped down the pain, a finding that might lead to new medications. The researchers will next study whether the protein plays a role in more long-lasting types of pain.
Treating at home
First-degree sunburns tend to peel in a few days. But more severe, second-degree burns can blister and even require a doctor's care, especially if they cover large areas or come with fever and chills, says Dr. Roger Ceilley of the American Academy of Dermatology and the University of Iowa. A bad burn hinders how well your body cools itself, so it's important to cool down and keep hydrated.
To self-treat the pain, take ibuprofen or similar over-the-counter painkillers known as NSAIDs within a few hours of reddening skin, Ceilley advises. Those pills fight various kinds of inflammation. While they may not directly block the pain-causing protein the British researchers discovered, they do act on related pain chemicals, he notes.
But don't use those pills before going in the sun; they're among a host of medicines that can make your skin more sun-sensitive.
Cool compresses can soothe, and some patients find relief from aloe.
But "you don't want to put a lot of heavy ointments on," Ceilley cautions. They can trap in heat.
At Wake Forest University, dermatology professor Dr. Steven Feldman also advises anesthetic sprays to numb the area, and a hydrocortisone cream for more serious burns.
But, more important, "Don't get a sunburn," Feldman stresses.
Did you know?
File Photo: AP/Mel Evans -- If you're outside this summer, chances are you've experienced an unfortunate rite of summer: the sunburn.