Exantems

Exantems, or exanthems, are diffuse skin rashes accompanying systemic illness. They are often widespread and may be feverish; the rash is typically morbilliform or maculopapular, though vesicular or urticarial patterns occur. The trunk is usually affected first and spreads to the face and limbs. The pattern, timing, and accompanying symptoms help differentiate infectious, drug-related, and other causes.

Viral exanthems are most common in children and include measles, rubella, roseola (HHV-6), and erythema infectiosum (parvovirus B19). Other viruses (enteroviruses) can cause fever with rash. Bacterial exanthems include scarlet fever (Streptococcus pyogenes). Drug-induced exanthems are common and may follow exposure to antibiotics or anticonvulsants, often developing days to weeks after starting the drug.

Diagnosis is usually clinical, supported by exposure history and vaccination status. When uncertain, labs or cultures may help; skin biopsy is rarely needed. Management centers on treating the underlying cause and relieving symptoms. Viral exanthems are managed supportively; bacterial causes require antibiotics; drug eruptions prompt discontinuation of the offending agent. Contagious diseases such as measles may require isolation.

Most exanthems resolve without lasting effects within days to weeks. Complications are uncommon but can be serious with measles or rubella in pregnancy or in immunocompromised individuals. Prevention relies on vaccination where applicable and avoidance of known drug triggers.