Symptoms of Roseola. 1  Most children get Roseola between 6 months and 3 years of age. 2  Rash: Pink, small, flat spots on the chest and stomach. Rash is the same on both sides of the body. 3  Classic feature: 2 or 3 days of high fever without a rash or other symptoms.  The rash starts 12 to 24 hours after the fever goes 1  away. The rash lasts 1 to 3 days.