ABSTRACT
The diagnosis of drug or chemical-induced photosensitization offers the opportunity of cure through removal of the chromophore. A range of mechanisms exist to explain how a therapeutic drug enhances the photosensitivity of cellular skin components. It does appear that phototoxicity, a nonimmunological event due to combination of a drug or metabolite, with light of appropriate wavelength, is the most commonly encountered mechanism. The incidence of phototoxicity due to systemic medication varies greatly from drug to drug and even within subjects taking a particular agent. It usually relates to drug dosage, the local intensity of the relevant wavelengths, and individual factors such as skin type and drug handling. As pharmacological drug handling does vary between subjects, it is not surprising that there are patients with more or less sensitivity with any group taking a particular phototoxic drug at a specific dosage. Phototoxic drugs do vary in the wavelength responsible for the clinical problem.
