In general, children who are simply frightened will not cause fever, but after being frightened will cause secondary fever, because children who are frightened will cause a temporary decrease in immunity, causing mental uncertainty and poor appetite for food, etc. The above factors will cause children’s immunity to be low secondary to various infections, such as infection with viruses, bacteria, Mycoplasma pneumoniae, etc.. After feeling the pathogenic bacteria, it will cause infectious fever, so the simple fright of children will not cause fever, but if it causes secondary infection will cause fever.