A baby’s hard tummy may be caused by flatulence, a condition that can be caused by both medical and surgical diseases. Internal diseases are mainly indigestion, acute gastroenteritis, etc. If the baby has a hard tummy, little exhaust, paroxysmal abdominal pain, or accompanied by vomiting, diarrhea, etc., it is mostly considered to be caused by digestive system diseases. You can massage and apply hot compresses to the baby’s stomach and use belly button patches. If accompanied by diarrhea, stool tests must be performed to exclude bacterial infection. In case of severe vomiting, fasting for 4-6 hours is required. If accompanied by fever, it is recommended to go to the pediatric internal medicine department for a face-to-face consultation, which requires routine blood and stool tests to clarify the diagnosis and then just treat the symptoms. If the baby has a hard stomach, no exhaustion, vomiting more frequently, abdominal pain not relieved, and poor mental status, you need to go to the pediatric surgical department for an interview, blood tests, and if necessary, an abdominal ultrasound to rule out intestinal obstruction, intussusception or pediatric appendicitis.