A child’s severe spitting up may be caused by physiological factors, or acute gastroenteritis, congenital hypertrophic pyloric stenosis and other causes. 1. Physiological factors: the child’s stomach capacity is relatively small, and the cardia between the esophagus and stomach is not yet mature. If the amount of milk fed at one time is too large and too fast, severe spitting up will occur. 2. Acute gastroenteritis: severe spitting up may be caused by acute gastroenteritis, which is usually associated with bacterial and viral infections and improper diet. Clinical symptoms include nausea, vomiting, abdominal pain, diarrhea and fever. 3. Congenital hypertrophic pyloric stenosis: a child’s severe vomiting may be caused by congenital hypertrophic pyloric stenosis. Congenital hypertrophic pyloric stenosis is an obstruction of the output tract caused by hypertrophy and edema of the pyloric muscle, with common symptoms such as loss of appetite, dehydration, abdominal mass, and projectile vomiting. If your child is spitting up severely and is accompanied by other discomforts, parents should take your child to the hospital in time to have the cause clarified and then treated under the guidance of the doctor.