Best dental clinic in 200 feet Radial road Causes of bleeding from gums If the gums bleed when you brush your teeth, there may be something wrong with your mouth. If your gums are healthy, it won’t bleed with a stimulus such as tooth brushing. The main cause of blood from the gums is periodontal disease. Periodontal disease is a disease in which bacterial infection occurs in the tissues that support the teeth, and the main symptom is an inflammatory reaction in the gums. Inflamed gums become swollen and easily damaged by even the slightest stimulus. This results in bleeding.