Children with fever and blisters in the mouth may be caused by herpes pharyngitis, hand, foot and mouth disease, chickenpox and other factors. 1. Herpes pharyngitis: children with low immunity are susceptible to infection by coxsackievirus or enterovirus, which causes damage to mucosal tissues in the nasal cavity and oral cavity and produces an inflammatory response, leading to the symptoms of blisters and fever in children’s mouths. 2. Hand, foot and mouth disease: viral infection can lead to inflammation in the respiratory or digestive tract, causing herpes on the palms of the hands, soles of the feet, oral herpes and fever. 3. Chickenpox: If a child comes into contact with someone who has chickenpox or is infected with the chickenpox virus, it can lead to blisters in the oropharynx. At the same time, the body will also be attacked by the virus and cause fever symptoms. In short, there are many reasons why children have blisters in the mouth and fever, it is recommended to go to the pediatrics department of the hospital in a timely manner in order to clarify the cause of the disease.