Waking up with blood in the mouth is mainly considered to be related to oral diseases, respiratory diseases and gastrointestinal diseases. 1. Oral diseases: such as gingivitis, oral ulcers and other diseases, can lead to the emergence of some inflammatory secretions in the affected area, or even pus and blood, and then the symptoms of cloudy saliva with blood. 2. Respiratory diseases: such as purulent tonsillitis, bronchial tumors and other diseases, may lead to the emergence of some pus and blood secretions in the affected area, after mixing with saliva, this symptom can also appear. 3. Digestive tract diseases: such as gastric hemorrhage and other diseases, there may be symptoms of vomiting blood, and then there are symptoms of cloudy saliva with blood. 4. Hematologic disorders: Coagulation disorders can lead to red, swollen and bleeding gums. This symptom may also be related to other diseases. It is recommended that the patient consult a doctor as soon as possible to confirm the diagnosis and provide targeted treatment.