There are several reasons for having blood in your saliva:1. Chronic gingivitis periodontitis. Gum bleeding is one of the most common symptoms of chronic gingivitis periodontitis, often with blood in the saliva when brushing teeth or without the action of any use trigger. The treatment for chronic gingivitis periodontitis is upper and lower gingival scaling to remove calculus and restore the health of the gums. 2. Leukemia, leukemia can lead to a large number of immature white blood cells filling the gums, causing gingival hyperplasia and gum bleeding, leukemia can be easily determined by routine blood tests, found bleeding gums, judged to be leukemia should promptly go to the hematology department. 3. chronic pharyngitis Patients with chronic pharyngitis often feel discomfort in the pharynx, dry cough, and in severe cases, congestion in the mucous membrane of the pharynx, which can lead to blood in the mouth, and the treatment for chronic pharyngitis is mainly anti-inflammatory treatment and nebulization. delaying the disease and making it worse.