Abstract
The sunlight can induce a variety of photo-biologic reactions in the skin. Any photobiologic reaction must be preceded by a photochemical reaction, which initiates after a certain chromophore absorbs light energy. Sunburn, suntanning, photoaging and ultraviolet-carcinogenesis can occur as physiologic reactions to the sunlight without exogenous photosensitizers or endogenous abnormalities. These changes occur as a sequence of events, but not independently. Therefore, it is important to protect the initial sunburn reaction to prevent the following photoaging and skin cancers.
