Spitting up blood in the morning is in most cases caused by bleeding gums, and the more common clinical condition of bleeding gums is gingivitis. Gingivitis is caused by poor periodontal hygiene and the presence of large amounts of plaque and calculus in the gums, especially in the gingival sulcus, which provide good conditions for bacterial growth. So the bacteria proliferate and cause inflammation of the periodontium and gums. The typical manifestation of gingivitis is the redness, swelling, tenderness and bleeding of the gums, which is most often manifested by bleeding under stimulation, usually during brushing and bleeding from biting hard objects. However, if gingivitis is relatively severe, spontaneous bleeding and sucking bleeding can also occur in relatively heavy areas, so it is also more common to have blood in the mouth and water in the morning.