Small blisters on the inside of children’s lower lips that don’t hurt or itch can be caused by oral herpes simplex, hand, foot and mouth disease, and mucous gland cysts. 1. Oral herpes simplex: an infectious disease of the oral mucosa and perioral skin caused by herpes simplex virus. The main manifestation is multiple blisters in the mouth, followed by ulcers, which may be accompanied by fever, swollen gums, pain and other symptoms, which leads to small blisters on the inside of the lower lip of the child painless. 2. Hand, foot and mouth disease: it is an acute infectious disease caused by enterovirus. The main manifestations are fever, scattered herpes on the oral mucosa, herpes or maculopapular rash on the hands, feet and buttocks, which can be accompanied by cough, loss of appetite, dyspnea and other symptoms, which can also cause small blisters on the inner side of the children’s lower lip without pain and itching. 3. Mucous gland cysts: It is a cyst formed when the excretory opening of the mucous gland that secretes mucus is blocked and the mucus cannot be discharged normally. Its main manifestation is the appearance of light blue-purple, translucent blisters in the oral cavity, usually not accompanied by pain, itching and other discomforts. It can also cause small blisters on the inside of the lower lip in children without pain or itching. There are many other causes of small blisters on the inner side of children’s lower lip that are painless and itchy, which should be taken seriously, and the cause of the blisters should be identified in time, and further treatment or therapy should be prescribed by the doctor.