Blood in the nostrils but no nosebleed means that the bleeding is not much and the clotting function is normal. It may be caused by dryness of nasal cavity or due to diseases such as nasopharyngeal cancer and sinusitis. 1. Nasal dryness: If you often pick your nose or stay in the environment with too high temperature for a long time, which leads to the decrease of nasal gland secretion, it will easily lead to nasal dryness, and you will easily have the situation of having blood in nostrils but no nosebleed. 2. Nasopharyngeal cancer: this disease is mainly caused by EBV infection, and research shows that it may also be related to heredity, frequent consumption of pickled food, environment and other factors. In the early stage of the disease, it may not cause any symptom, but with the further development of the disease, patients will have the symptom of blood in the snot, which may be manifested as blood in the nostrils but not nosebleed, and there will also be the symptom of tinnitus, nasal congestion and so on. 3. Sinusitis: the occurrence of this disease is related to pathogenic bacteria infections, such as pneumococcus, staphylococcus, katatococcus, and so on, but also with the neighboring organ infections, trauma, surgery, vitamin deficiencies, etc., which can be induced by smoking, air pollution, etc., leading to the patient to appear in the pus with a little blood, nasal congestion, decreased sense of smell and other symptoms. If there is blood in the nostrils but no nosebleed, it is recommended to go to the hospital for diagnosis and treatment.