Children who develop roseola usually do so after having a minor upper respiratory illness. Although the condition typically causes symptoms, children with a very mild case may show no symptoms at all.

Initially, the primary symptom is a substantial fever. It is not uncommon for the child’s temperature to rise to over 103 degrees Fahrenheit (39.5 degrees Celsius) and even up to 105 degrees Fahrenheit (40.6 degrees Celsius). This fever usually lasts about three days but may last for as long as a week to 10 days, causing the child to become fussy and irritable. Lack of appetite, a sore throat, a runny nose and swollen lymph nodes in the neck are also common with this fever. Other symptoms may include fatigue, mild diarrhea and swelling of the eyelids.

In a minority of cases, the fever may trigger convulsions known as febrile seizures. These can cause the child to lose consciousness while the arms, legs or face jerk and twist for several minutes. The child may also lose bladder or bowel control.

After the fever has continued for a few days, it typically breaks suddenly. When this happens, a raised rash usually begins to appear on the child’s trunk and spreads across the body, especially to the neck, face, arms and legs. This rash is usually pinkish-red and individual spots may turn white when touched. Spots often have what appears to be a halo surrounding them. The rash does not itch or cause discomfort. It may last from anywhere from a few hours to several days.

Symptoms in adults tend to be milder than those in children and often resemble those of mononucleosis, a disease involving excess numbers of white blood cells that is characterized by fever and swollen lymph nodes.