Adverse Cutaneous Drug Reactions

Drug-induced skin reactions include a range of allergic and nonallergic undesirable manifestations on the skin and mucous membranes resulting from the administration of a certain drug. Drug allergies are mediated by all four types of allergic hypersensitivity, but they most often occur due to type I reactions. An exanthematous (maculopapular) eruption is the most common drug hypersensitivity reaction. Other forms of allergic hypersensitivity to the drug include urticaria and angioedema, fixed drug eruption, and in rare cases, acute generalized exanthematous pustulosis and drug reaction with eosinophilia and systemic symptoms. In addition, there is a group of immune-mediated drug reactions characterized by varying degrees of skin and mucosal involvement, including erythema multiforme, Stevens–Johnson syndrome, and toxic epidermal necrolysis. Among them, toxic epidermal necrolysis is the most severe skin reaction, characterized by blistering and extensive exfoliation of the skin and mucous membranes.