There are the following possibilities for blood in the mouth: First, the most likely cause is suffering from chronic periodontitis. The more typical symptom of chronic periodontitis is spontaneous bleeding of the gums, mainly in the morning, when blood is found in the mouth when brushing teeth or spitting out froth. This is a good time to visit a periodontist for an examination. If it is true that the accumulation of more calculus leads to gum redness, swelling, overflowing pus, bleeding, and even the loss of alveolar bone, we should promptly carry out systematic periodontal treatment, and the bleeding will naturally heal after the periodontal inflammation disappears. Second, oral bleeding should never be ignored, is not the bleeding in the nasal cavity caused. If there is often blood in the nasal cavity, patients must pay more attention to the ENT department in a timely manner to clarify the diagnosis, if necessary, to take a CT of the nasal cavity. third, there is blood in the mouth, or to check the pharynx, digestive system and trachea whether there are symptoms of discomfort.