Parents are urged to seek medical care if their child has a fever that lasts more than a week, or a rash that remains after three days. Anytime a child has a fever over 103 degrees Fahrenheit (39.5 degrees Celsius) parents should consult a physician.

In diagnosing roseola, a physician will perform a complete physical examination and compile a thorough medical history. In rare cases, a blood test may be performed to confirm the presence of antibodies associated with roseola. This may be necessary, as many other childhood illnesses (e.g., ear infection, common cold) can mimic the initial symptoms of roseola. This is particularly true in instances when the child does not develop the rash typically associated with roseola.