What is the most common type of cutaneous drug eruption?

The most common type of cutaneous drug eruption is indeed the exanthematous or morbilliform rash. This type of rash typically manifests as a generalized, symmetric eruption that resembles measles. It often begins with macules and papules that may spread, appearing on the trunk and extremities.

This type of eruption is commonly associated with the administration of a variety of medications, including antibiotics (especially penicillins and sulfonamides), anticonvulsants, and nonsteroidal anti-inflammatory drugs (NSAIDs). The pathophysiology involves a hypersensitivity reaction, often Type IV (delayed-type hypersensitivity), where the skin reacts to an antigenic stimulus from the drug.

The significant prevalence of this rash among drug eruptions, alongside its benign nature, contributes to its recognition as the most common type. Although other types of drug eruptions, such as urticarial eruptions or erythema multiforme, can occur, they are less frequently encountered in the context of cutaneous reactions to medications. Overall, understanding the common presentations of drug eruptions is critical in clinical practice, as it aids in the prompt identification and management of such reactions.