A new discovery could lead to treatments that bring an end to the pain of sunburn, scientists say.
Researchers have identified a molecule in the skin that is largely to blame for the painful effects of staying too long in the sun.
Blocking the molecules, called TRPV4, could provide a way to combat the burning sensation and possibly several other causes of pain.
"We have uncovered a novel explanation for why sunburn hurts," said US lead scientist Dr Wolfgang Liedtke, from Duke University School of Medicine.
"If we understand sunburn better, we can understand pain better."
Most cases of sunburn are caused by ultraviolet B (UVB) radiation. In moderation, this component of sunlight benefits the body by boosting levels of vitamin D.
But too strong a dose of UVB can damage DNA in skin cells, increasing susceptibility to cancer.
Sunburn is nature's way of telling us to find some shade.
Liedtke's team genetically engineered mice to lack TRPV4 in their skin and exposed their hind paws - which most resemble human skin - to UVB rays.
The mutant mice suffered little sensitisation and tissue injury, while normal animals became hypersensitive and blistered.
Next the scientists produced a drug that selectively inhibits the molecule and applied it to the paws of normal mice in a solution of alcohol and glycerol.
Treated mice were largely resistant to the pain-inducing and skin-damaging effects of sunburn.
Research on human skin samples has shown increased activation of TRPV4 after UVB exposure.
The researchers, whose findings are reported in the journal Proceedings of the National Academy of Sciences, say more work is needed but envisage sun screens containing TRPV4-blockers to protect against burning.
"I think we should be cautious because we want to see what inhibition of TRPV4 will do to other processes going on in the skin," said Liedtke.
"Once these concerns will be addressed, we will need to adapt TRPV4 blockers to make them more suitable for topical application. I could imagine it being mixed with traditional sunblock to provide stronger protections against UVB exposure."