Which of the following is an offending agent for maculopapular rash?

• A. Penicillin/cephalosporins
• B. Aspirin
• C. Lisinopril
• D. Metformin

Answer: (A)

Maculopapular drug eruptions are common immune-mediated skin reactions to medications, usually arising from a delayed-type (cell-mediated) hypersensitivity. After exposure to the offending drug, sensitized T cells trigger inflammation in the skin, leading to a symmetric, diffuse erythematous rash with both macules and papules. The classic offenders for this pattern are beta-lactam antibiotics, such as penicillins and cephalosporins, because these drugs most commonly provoke this type of exanthem. Aspirin can cause rashes or urticaria in some people, but it’s not as characteristically linked to a maculopapular pattern. Lisinopril may cause rash in rare cases, but it’s better known for angioedema and cough. Metformin is not a typical cause of maculopapular eruptions. Thus, penicillin/cephalosporins are the best match for an offending agent producing a maculopapular rash.