Why do sunburns itch?

Special nerves: Sunburn damages the surface layer of your skin. This outermost area is loaded with special nerve fibers called c-fibers, that respond to itch. (itch is a mechanism to protect us agains insects and other minor injuries that aren't significant enough to register as pain). Because sunburn skin damage happens in this surface layer, these nerves fire furiously until the skin is healed over again.

Related to healing: Sunburn occurs when the radiation from the sun damages the skin and the many things which is the bodies way to promote healing through getting good blood there and damaged things out. As healing occurs, the nerves in the area react to the healing causing an irritation that we interpret as itching. A good anti-burn ointment gently applied will help minimize the itching. Don't scratch the burn !

Release of ....: ...Inflammatory chemicals from the burn wound, such as histamines and prostaglandins.