Researchers at King’s College London have found a molecule in the body which controls sensitivity to pain from UVB irradiation, identifying it as a new target for medicines to treat pain caused by other common inflammatory conditions such as arthritis.
The molecule, called CXCL5, is part of a family of proteins called chemokines, which recruit inflammatory immune cells to the injured tissue, triggering pain and tenderness. This is the first study to reveal this molecule’s role in mediating pain.
This is a basic science article, but it is worth reading and explains why NSAIDs like ibuprofen may help. Don't use naproxyn, however. There's a small chance of photosensitivity with that drug.
See news article on study: Sunburn study could lead to new pain relief (7/7/2011)