Non-melanocytic hyperpigmentations (dyschromias), besides common melanotic ones, develop mostly due to the
skin reaction to various chemicals and/or drugs of exogenous origin. They can be however also caused by some
endogenously formed (evolving) intermediates of several metabolic diseases. The above mentioned factors are of
toxic or allergic character and their clinical dermal manifestation often occurs as an allergic reaction after the
exposition of the skin to solar radiation, or as a toxic contact reaction both on the skin and the mucosa. As
a therapy of individual skin changes is difficult or impossible, the only treatment consists in reliable
pigmentation, hyperpigmentation, phototoxicity, photoallergy, photoprotection.