[Coda]

Some people actually do have a sunlight sensitivity beyond just sunburning easily. Most of the time it has something to do with Vitamin D metabolism; the human body uses sunlight on the skin to produce its own Vitamin D. Some medications have warnings to avoid sunlight for that reason.

It's not technically an allergy because it doesn't trigger a histamine reaction in the body, but it's sufficient to call it an allergy in casual discussion because people understand what that means.