[Alarm signs in drug-induced skin reactions]

Drug-induced skin reactions may represent warning signs in three different situations. First, the cutaneous rash may reveal an underlying systemic disease being perhaps still undiagnosed. The following examples illustrate this concept: the drug-induced eruption observed in patients suffering from infectious mononucleosis, from lymphoproliferative malignancy or from HIV infection. Second, the cutaneous rash may indicate a drug-induced multisystemic disease possibly more severe than the cutaneous symptoms. Third, the cutaneous rash may herald the most severe drug-induced skin reaction, Lyell syndrome, due to epidermal necrolysis probably of immunological origin.