Blisters at the corners of a child’s mouth can be a herpes virus infection or a manifestation of stomatitis. The common cause of blisters at the corners of the mouth in children is herpes simplex virus infection, a manifestation of oral lip herpes, which occurs in the lips and corners of the mouth, and is associated with colds and fevers or nervousness and fatigue. Lack of sleep or emotional depression makes the immune system weak and predisposes to infection. The clinical symptoms are clusters of pinpoint papules at the corners of the mouth, sometimes breaking down to reveal yellow fluid, and localized pain and itching. Sometimes symptoms of low-grade fever may occur. Herpes simplex virus infection is prone to recurrence in the same location, and this condition can be treated with oral antiviral oral solution or by applying acyclovir ointment to the affected area. The common cause of corners of children’s mouth blisters may also be corns, corns is malnutrition or vitamin, trace element deficiency, especially vitamin B2; can also be caused by diabetes, anemia and other systemic factors; infection is also very common: caused by bacteria, viruses, fungi and other pathogenic microorganisms, the most common is caused by Candida albicans, Staphylococcus aureus and streptococcus. Malnutrition keratitis should be given appropriate medication according to its etiology, such as vitamin supplementation, folic acid, etc. to treat systemic diseases, and can be treated locally with 0.1% ezacridine lactate wet compresses, coated with povidone-iodine or antibiotic ointment. Stomatitis due to bacterial infection can be treated with topical antibiotics, such as aureomycin ointment or erythromycin ointment applied topically. Fungal keratitis can be applied topically with miconazole cream or clotrimazole ointment. The specific medication, please combine with clinical, to the doctor’s face to face guidance shall prevail. So children with blisters at the corners of the mouth may be herpes simplex virus infection, or may be malnutrition or bacterial or fungal infection caused by stomatitis.