The reasons that cause 3-year-old babies to vomit even when they drink water may be related to acute gastroenteritis, intestinal obstruction and other factors, and it is necessary to choose the appropriate treatment according to the specific condition. 1. acute gastroenteritis: if the 3-year-old baby diet unclean or eat spicy and stimulating food, so that pathogenic microorganisms into the gastrointestinal tract caused by acute gastroenteritis, so that the gastrointestinal tract smooth muscle spasm, easy to lead to drink water and vomiting, keep a light diet, can be recommended by the doctor to use probiotics and other medications to relieve, if necessary, with antibiotic treatment. 2. intestinal obstruction: if the 3-year-old baby intestinal adhesions, inflammation, the presence of food residues in the intestinal tract can not be discharged from the body in a timely manner, there will be abdominal pain, constipation, drinking water and vomiting, etc., can be recommended by the doctor, through the intravenous injection of dextrose solution, sodium chloride solution, such as timely replenishment of the body’s water and electrolytes, the situation is more serious, you can be treated through surgery. 3-year-old baby drink water also vomit may also have other reasons, such as encephalitis, meningitis, etc., it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment. The use of medication should follow the doctor’s instructions.