There are many reasons for vomiting blood-colored water to the back, including oral bleeding, throat bleeding, bronchial bleeding and gastrointestinal bleeding. The details are as follows: 1. Oral bleeding, generally bleeding gums, bleeding oral ulcers, bleeding buccal mucosa, blood in the mouth and saliva mixed will spit out blood-colored water, to promptly go to the Department of Dentistry for related treatment, usually pay attention to maintain oral hygiene. 2. Throat and bronchial bleeding, the capillaries of the mucous membrane in the throat are congested and bleed when coughing and violent vomiting, such as chronic pharyngitis, bronchitis, etc. The symptoms are coughing, coughing up blood, blood in sputum, and sometimes fever. 3. Gastrointestinal bleeding, manifested as abdominal discomfort, abdominal distension and pain, acid reflux, belching, eructation, nausea, vomiting, loss of appetite, body wasting, etc. The vomit is coffee-colored objects, and can also be accompanied by black stool.