Common causes of vomiting and fever in young children include acute gastroenteritis, respiratory infections and encephalitis. 1. Acute gastroenteritis: because the gastrointestinal function of young children is not perfect, poor resistance, if the diet is not clean or eat irritating food, it is likely to produce gastrointestinal infections, resulting in acute gastroenteritis, which is manifested in fever, vomiting, diarrhea, abdominal pain and other symptoms. 2. Respiratory tract infections: mostly due to the invasion of bacteria, viruses and other pathogens, its main symptoms include fever, cough, phlegm, sore throat and so on. As the digestive system of young children is very imperfect, pathogenic bacteria can easily spread to the digestive tract through the respiratory tract, leading to gastrointestinal dysfunction, and then vomiting and other digestive symptoms. 3. Encephalitis: If the baby’s central nervous system is infected, it may cause encephalitis and other diseases, which may lead to persistent high fever, nausea, projectile vomiting, etc., and the baby with severe symptoms may even become comatose and have impaired consciousness. All in all, if a toddler vomits and has a fever, it is recommended that he or she be taken to the hospital immediately for a clear diagnosis and treatment for the cause.