Bleeding gums can be caused by improper brushing, gingivitis, periodontitis and other reasons. 1. Improper brushing: brushing teeth with too much force or preferring to use a hard-bristled toothbrush, which will break the gums and cause bleeding gums when brushing teeth. 2. Gingivitis: Gingivitis patients often have bleeding gums when brushing, sucking, biting hard objects or picking teeth. It is because the gums are stimulated by the outside world for a long time, resulting in swelling and congestion of the gums, but the bleeding is usually not big and usually stops soon. 3. Periodontitis: food in the mouth for a long time can not be dealt with, it will cause the growth of bacteria, resulting in inflammation of the gum tissue, which is common redness and swelling of the gums, there will be the case of brushing gums bleeding, plaque calcification to form calculus, stimulate the periodontal tissues, resulting in periodontitis, easy to bleed when stimulated. Lead to brushing gums bleeding, there may be a lack of vitamins, gum trauma, thrombocytopenia, etc., the patient should go to the regular hospital stomatology clinic in a timely manner, to identify the cause of the disease, under the guidance of a professional doctor for targeted treatment.