How long does it take to sunburn?

LOL! Yes, it can be that serious. As most of us probably know, UV light is the culprit (UVB being more damaging to the skin, and UVA less). However, contrary to what many people think, lower levels of melanin is not the only factor that increases a person's chance of sunburn. Just a few examples of "non-melanin" factors: antibiotics, medicated soaps and creams, birth control pills, prior/recent sun exposure and skin injury. Anyway- Of course, certain light-skinned (and fair-haired) people are at higher risk of sunburn. There ARE individuals who burn in less than 10 minutes. It happens to me unless I've "browned up" a bit. I usually don't use sunblock that's less than SPF 45.