If you think your child has a fever but you are not able to measure his or her temperature, it is important to look for other symptoms of illness. Children tend to run higher fevers than adults. The degree of fever may not indicate how serious your child's illness is.With a minor illness, such as a cold, a child may have a temperature of 104°F (40°C) , while a very serious infection may not cause a fever or may cause only a mild fever.f you think your child has a fever but you are not able to measure his or her temperature, it is important to look for other symptoms of illness. Children tend to run higher fevers than adults. The degree of fever may not indicate how serious your child's illness is.