It typically happens with a mild sunburns well away from blistering, however more severe burns can result in an itch lasting almost a week. This is not sun poisoning, nor is it an allergic reaction. The condition can last anywhere from 12 to 48 hours, where the first day is always the worst, and is gone as if it had never shown up. It can be fierce enough to cause muscle spasms, but in most cases, the experience is best described as truly maddening. Reliably 2-3 days after a reasonably mild (non-blistering) sun burn. A swarm of fire ants biting you from the inside.Īcute, unimaginable, itching that occurs in short, intense waves. Described as having razor sharp sand paper rubbing beneath your skin.