What in the blood could make you throw it up?

Vomiting blood? ER. Vomiting blood suggests bleeding coming from the stomach, esophagus, or (less commonly) mouth or nasopharynx. It can be a sign of a bleeding ulcer. In people with liver disease, it can be a sign of bleeding varices (distended veins in the esophagus). Vomiting blood or material resembling coffee grounds (partially digested blood) really needs immediate evaluation, preferably in er.