Roseola is a generally mild infection that usually affects children by age 2. It occasionally affects adults. Roseola is extremely common — so common that most children have been infected with roseola by the time they enter kindergarten.

Two common strains of the herpes virus cause roseola. The condition typically causes several days of fever, followed by a rash.

Some children develop only a very mild case of roseola and never show any clear indication of illness, while others experience the full range of symptoms.

Roseola typically isn't serious. Rarely, complications from a very high fever can result. Treatment of roseola includes bed rest, fluids and medications to reduce fever.