A few days after the fever appeared mouth ulcers, may be infected with herpes simplex virus caused by primary herpetic gingivostomatitis, the patient first appeared fever symptoms, followed by blisters occurring in the oral mucosa, the blisters can be broken to form ulcers, as follows. Primary herpes gingivostomatitis usually first appear fever, headache, fatigue, general muscle pain and other acute symptoms, about 1 ~ 3 days later, the oral mucosa occurred extensive congestion and edema, can occur in clusters of small blisters, blister wall is thin and easy to break, the formation of irregular vesicles, if the secondary infection occurs, then the formation of ulcers. A few days after the fever appeared mouth ulcers may have other reasons, it is recommended to go to the hospital in time.