A very common cause of vomiting is gastroenteritis, an inflammation of the gastrointestinal tract which, while painful, is not a serious medical condition. The nausea lasts for more than a few days or there is a possibility of pregnancy. Personal treatments are not effective, you suspect dehydration, or a known injury has occurred, causing vomiting. Vomiting lasts for more than a day, or accompanying diarrhea lasts for more than 24 hours. For infants, vomiting lasts more than a few hours, diarrhea and signs of dehydration are present, there is a fever higher than 100 °F (38 °C), or if the child hasn't urinated for six hours. For children over age six, vomiting lasts more than 24 hours, diarrhea combined with vomiting lasts for more than 24 hours, there are signs of dehydration, there is a fever higher than 102 °F (39 °C) or the child hasn't urinated for six hours. You see blood in the vomit (bright red or "coffee grounds" in appearance). You have severe headaches or a stiff neck. You experience lethargy, confusion, or a decreased alertness. You experience severe abdominal pain. You count a fever over 101 °F (38 °C). You measure rapid breathing or pulse. Bulimia is the urge to vomit after eating in order to control weight. People with Bulimia eat large amounts of food in a short time (binge) and then find a way to get rid of the food (purge). Bulimia is treated with psychological counseling, but is curable.

TL;DR in Vietnamese:
Biết rằng hiện tượng nôn hầu như là bình thường, nhưng một số trường hợp có thể là dấu hiệu của các vấn đề nghiêm trọng hơn về sức khỏe. Gọi cho bác sĩ hoặc y tá để nói về tình trạng của bạn nếu: Tìm cấp cứu ngay nếu: Nhờ sự tư vấn của chuyên gia nếu bạn nghĩ mình có thể mắc chứng rối loạn ăn uống như bulimia (chứng ăn – ói).