Which cutaneous drug eruption typically occurs within minutes to hours after drug administration?

Urticaria, commonly known as hives, and angioedema are types of cutaneous drug eruptions that manifest within a short time frame—typically minutes to a few hours after the administration of the offending medication. This rapid onset is due to the immediate hypersensitivity reaction, often mediated by immunoglobulin E (IgE) antibodies and the release of histamine and other inflammatory mediators from mast cells.

In clinical practice, recognizing this timing is critical as it helps differentiate urticaria from other drug-related skin reactions, which may develop over days to weeks following exposure. For example, erythema multiforme, exanthematous rash, and contact dermatitis generally present later, often taking days to appear. This distinction aids in swift treatment and avoidance of the triggering drug. Additionally, urticaria can be associated with systemic symptoms such as pruritus, which enhances the clinical picture and calls for immediate evaluation and management.