Tanning occurs when ultraviolet radiation is absorbed by the skin, causing an increase in the activity and number of melanocytes, the cells that produce the pigment melanin. Melanin helps to block out damaging rays up to a point. Those with lighter skin are more likely to burn. Too much sun exposure in a short period causes blood vessels to dilate, resulting in sunburn. A sunburn causes skin redness, tenderness, pain, swelling, and blistering.
Sunburn becomes a more serious problem with fever, chills, upset stomach, and confusion.
If these symptoms develop, see a doctor. Scientists now believe that both UVA and UVB can cause sunburn, damage the skin, and lead to skin cancer. Other products protect only against UVB, previously thought to be the only damaging type. Some cosmetics, such as some lipsticks, also are considered sunscreen products if they contain sunscreen and their labels state they do. Sunblock products block a large percentage of UV radiation.