The dark brown substance vomited after drinking may be food, medicine or blood. 1. Food: If you eat some dark-colored food, such as animal blood and animal liver, before or while drinking, after drinking, these undigested and unabsorbed food may be vomited out because of stomach contraction and spasm. 2. Drugs: may be taking bismuth or some traditional Chinese medicines, after drinking alcohol, the drugs will be vomited out appearing dark brown material. 3. Gastrointestinal bleeding: because alcohol can cause some stimulation to the gastric mucosa, leading to gastric mucosal damage, and may even cause bleeding, when the blood is oxidized, a black-brown substance will be formed, especially if the patient himself suffers from gastritis, gastric ulcer patients are prone to this situation. If the black substance vomited after drinking is caused by gastrointestinal bleeding, you need to go to the hospital in time and cooperate with the doctor to take treatment.