Exanthematous, or morbilliform, eruptions are the most common of all medication-induced eruptions. In children, 10%-20% of exanthematous eruptions are attributed to a medication. The eruption consists of red blanching macules and papules that begin on the head and trunk and spread symmetrically caudally and to the proximal extremities. In severe eruptions, lesions coalesce and may lead to generalized erythroderma. Palms and soles may also be involved. Pruritus is common, and fever may occur in more severe reactions. Onset is usually within 7-14 days of initiating a medication, although it is not uncommon for exanthematous penicillin reactions to develop after 2 weeks from the onset of exposure.

Almost any oral agent can cause an exanthematous reaction, but they are most commonly seen with the use of antibiotics (penicillins and sulfas), allopurinol, phenytoin, barbiturates, chlorpromazine, carbamazepine, d-penicillamine, captopril, naproxen, and piroxicam, but many other drug culprits have been reported, such as older and newer chemotherapeutic agents, including from immunotherapies and targeted therapies (referred to as "maculopapular eruption" in the oncologic literature).

Related topics: cutaneous adverse effects of BRAF inhibitors, cutaneous adverse effects of immune checkpoint inhibitors, cutaneous adverse effects of mTOR inhibitors