It is common for babies to have blisters at the corners of the mouth during a fever, so you should take your child to the hospital for a specific examination to determine the type of blister and the cause of the blister. In most cases, it is because the child’s resistance is weak during the fever, and the herpes simplex virus, which is normally hosted around the mouth, can easily take advantage of the opportunity to infect the body and cause blistering at the corners of the mouth. Treatment with antiviral medication is often effective and can be done orally with the Four Seasons Antiviral Combination or Ribavirin granules. In addition, for the symptoms of fever need to use antipyretic drugs to strengthen the resistance. If the temperature of fever is high, above 38.5 degrees, oral ibuprofen suspension or acetaminophen granules are recommended. If the temperature of fever is low, below 38.5 degrees, you can take oral treatment with pediatric black beetle and clear fever granules or pediatric antelope granules. If the symptoms of blistering at the corners of the mouth are more serious, you can also use erythromycin ointment to apply, which is also more effective.