Drug eruptions occur in papulosquamous, eczematous, vesiculobullous, and urticarial forms.
Many different drugs can cause the same kind of eruption. Specific classes of drugs, such as nonsteroidal anti-inflammatory agents, can cause a wide variety of both cutaneous and noncutaneous reactions. Drug eruptions can be classified on the basis of their pathogenesis, which may be immune mediated or, more commonly, nonimmunologic. Immunologic drug reactions may also be mediated by immune complexes or involve cytotoxic or cellular immune mechanisms. For example, progesterone sensitivity was identified as a cause of recurrent anaphylaxis in a patient who was not receiving the hormone.