Spitting with blood for a while and then gone may be gum disease, throat disease, lung disease and other causes. 1. Gum disease: common gingivitis, chronic inflammation in the gums, chewing, touching or brushing teeth, will stimulate the gums, resulting in spitting with blood a moment gone phenomenon. 2. Pharyngeal diseases: due to the inflammatory reaction, the mucous membrane of the throat appears congestion, edema and inflammatory material exudation, and even capillary rupture, this time there will be spitting with blood a moment of the symptoms are gone. 3. Lung diseases: such as tuberculosis, lung cancer, bronchiectasis and other diseases. Due to coughing caused by the rupture of capillaries in the lungs, thus appearing to spit blood, and a while after the situation. Spit with blood in the saliva of the patient, should promptly go to the regular hospital, identify the cause of the disease, under the guidance of professional doctors to take targeted treatment.