Blood in the nasal mucus is usually caused by dry nasal mucous membrane erosion, pathogen attack, vitamin deficiency, tumor and so on. 1. Nasal mucosal dryness and erosion: due to the dry environment of the nasal cavity, it is easy to lead to the mucosal blood vessels are relatively brittle, and then the capillary rupture, there will be a small amount of blood or blood clots. 2. Pathogen invasion: After a cold, viruses will invade the blood vessels of the nasal mucosa, causing blood vessel rupture and a small amount of bleeding. 3. Vitamin deficiency: when the body lacks of vitamins, the resistance of nasal mucosa will also be reduced, which is easy to be invaded by germs, resulting in blood in the nasal mucus. 4. Tumor: when the blood vessels of the tumor are damaged and bleed, it will lead to the situation that there is blood in the nasal mucus after sucking back the nasal cavity. It is recommended to use saline to rinse the nasal cavity to maintain a moist environment and lubricate the mucous membrane of nasal cavity. Go to the hospital in time for further examination to clarify the cause of the disease and then symptomatic treatment.