Bleeding from brushing teeth can be caused by vitamin C deficiency, periodontitis, or blood disorders. 1. Vitamin deficiency: Bleeding from brushing teeth may be caused by gum bleeding due to vitamin C deficiency. 2. Periodontitis: For example, local infectious diseases such as gingivitis, pulpitis, apical inflammation, etc., under the stimulation of plaque, will cause the expansion of the gum capillaries and congestion, which will also cause bleeding symptoms of brushing teeth. 3. Blood diseases: for example, idiopathic thrombocytopenia, hemophilia, leukemia and other diseases, may also cause bleeding from brushing teeth. There may be other reasons for bleeding from brushing teeth, you need to go to the hospital in time for examination, and follow the doctor’s instructions for treatment.