Which characteristic distinguishes a phototoxic skin reaction from a photoallergic one?
Answer
It is dose-dependent, meaning the severity increases with more medication or sun exposure
Phototoxicity is a chemical reaction where a substance in the body absorbs UV energy and directly damages the surrounding skin cells, creating a result similar to an exaggerated sunburn. Because the damage is directly related to the amount of the chemical present and the intensity of the UV light, it is dose-dependent. In contrast, photoallergy is an immune-mediated response that is not dose-dependent; once the immune system is primed to recognize the UV-altered chemical as an invader, even minimal exposure can trigger a reaction.
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