In general, the severity of a rash and fever does not relate to the
severity of an illness. It is important to find out how ill the child feels or
how the child is behaving.
Many viral illnesses can cause a rash and a fever of
103°F (39.4°C) or higher for
short periods of time (up to 48 to 72 hours). If a rash and fever are the only
symptoms, a fever of up to
101°F (38°C) that comes and
goes or lasts for up to 72 hours is usually not a cause for concern.
Newborns have immature immune systems. When they have fevers, they
need to be evaluated sooner than older children with fevers. A fever that
occurs with a rash in a newborn is impossible to assess over the telephone. A
visit to a health professional is required.
High, persistent fevers are more likely to indicate a serious problem
that requires a visit to a health professional. A persistent fever may be a
symptom of a serious infection.
A rash that looks like a sunburn and that starts 2 days after a fever of 102°F (38.9°C) or higher may be caused by a rare condition called toxic shock syndrome.