Why does sunburn hurt?

THAT'S THE WHY: You have probably seen that person - maybe you have even been that person. The one who got carried away on holiday and bared vast tracts of lily-white skin to the UV of the midday sun for too long while splashing in the water. Or maybe fell asleep by the pool and missed a few rounds of sunscreen.

The next morning, that person teeters gingerly down to breakfast, the sight of their lobster-hued skin enough to make onlookers wince.

There are plenty of good reasons not to get sunburn, and one of the most immediate is that it hurts.

Now scientists at King’s College London have identified a protein that appears to be involved in mediating that pain. They discovered that a gene called CXCL5 is induced strongly in human skin following UVB radiation.

In a study published online this month in Science Translational Medicine, when CXCL5 was injected into an animal model, it appeared to recapitulate the type of hypersensitivity triggered by UVB exposure.

“These findings have shown for the first time the important role of this particular molecule in controlling pain from exposure to UVB irradiation,” says researcher Prof Steve McMahon in a release.

“But this study isn’t just about sunburn – we hope that we have identified a potential target which can be utilised to understand more about pain in other inflammatory conditions like arthritis and cystitis.

“Im excited about where these findings could take us in terms of eventually developing a new type of analgesic for people who suffer from chronic pain.”