Waking up with blood in the saliva may be caused by oral diseases, throat diseases and digestive system diseases. 1. Oral diseases: such as oral ulcers, periodontitis, gingivitis and gingivoma may cause bleeding in the oral mucosa and gums, leading to the symptom of waking up with blood in the saliva. 2. Pharyngeal diseases: if the patient has acute pharyngitis, acute laryngitis and other inflammatory diseases, may cause the patient’s throat mucosa bleeding phenomenon, which leads to the patient woke up with blood in the saliva. 3. Digestive system diseases: If the patient has reflux esophagitis, gastritis and other diseases, when the inflammation is more serious, it may also cause the patient to wake up with blood in the saliva. There are many reasons that can cause patients to wake up with blood in the saliva, in addition to the above, there may also be other diseases, it is recommended that patients go to the hospital in time for a detailed examination, to clarify the cause of the disease, and targeted treatment.