The infectiousness of HFMD is two weeks, and the infectiousness will disappear after at least two weeks of isolation, that is, two weeks when the body temperature is normal and the rash has completely disappeared. In other words, HFMD is not contagious after two weeks, and most children with HFMD are mildly ill, recovering exceptionally well and with a relatively good prognosis. If there is a tendency of severe illness, the child should be treated actively. The tendency of severe illness is that the child has high fever, is less than 3 years old, has poor mental status, has convulsions, and has high blood count in laboratory tests. And one should be alert to the development of central nervous system or pulmonary or cardiac complications, which are high-risk factors for poor prognosis.