Vomiting after drinking coffee can be caused by coffee intolerance, coffee allergy, acute gastroenteritis and other factors. 1. Coffee intolerance: If you are intolerant to coffee, drinking it will lead to increased intestinal peristalsis, causing diarrhea, vomiting, nausea, etc. Symptoms will be gradually relieved after you stop eating. 2. Allergy to coffee: Coffee mainly contains caffeine, protein, tannic acid, etc. If you are allergic to a certain ingredient, it will cause allergic reaction after eating, which will easily lead to nausea and vomiting. 3. Acute gastroenteritis: If you are suffering from acute gastroenteritis, your condition has not recovered, and the symptoms will be significantly worse after drinking coffee, mainly related to gastric mucosal stimulation, if not handled in a timely manner, it will also cause abdominal pain and diarrhea. Drinking coffee and vomiting, can temporarily stop drinking, and regular observation; if the symptoms do not disappear, it is necessary to consult a doctor in time.