Vomiting with coffee brown vomitus is seen in

Fulminant poisoning by oxalic acid If the person is consumes large doses ie more than 20gm or more, death may occur due to circulatory collapse. There will be sour bitter taste in the mouth, a sense of constriction in the throat, epigastric pain and abdominal pain. The person will have nausea, eructation and vomiting with coffee brown vomitus. There may be severe thirst and abdomen will be tender. Ref: FORENSIC MEDICINE AND TOXICOLOGY Dr PC IGNATIUS THIRD EDITION PAGE 412