Roseola is an infection caused by a virus. It is characterized by a sudden onset of high fever followed by a rash. The infection usually ends on its own without complications.

Roseola
Nucleus factsheet image
Copyright © Nucleus Medical Media, Inc.

Roseola is usually caused by a virus called human herpesvirus 6 (HHV-6). It can also be caused by human herpesvirus 7 (HHV-7). These viruses are not the same as the herpes viruses that cause cold sores or genital herpes.