Erythema infectiosum, or fifth disease, is a common illness in young children due to infection with parvovirus B19. Infection can result in a mild exanthem, no exanthem, or the typical "slapped cheeks" rash.

The illness is biphasic, with a prodromal headache, low-grade fever, myalgias, rhinorrhea, and malaise beginning 7 days after infection, with symptoms lasting up to 5 days. The second phase begins about 1 week after the first phase begins and is comprised of the characteristic slapped-cheek facial rash followed by a lacy, reticulated body rash and/or arthralgias. Children recover spontaneously without therapy.

Individuals who are in early pregnancy (up to 21 weeks pregnant) and those who are immunocompromised or have a hemoglobinopathy are at elevated risk for complications.