There are many causes of blood in the nostrils. The more common causes are caused by dryness of the nasal cavity and erosion of the nasal mucosa, and some patients are caused by rupture of capillaries and bleeding in the nasal cavity. Some patients are caused by inflammatory reactions in the nasal cavity and sinuses, some patients are caused by bleeding nasal polyps and nasal hemangioma, and some patients are caused by nasopharyngeal cancer, and there are some individual differences in the specific causes. After the onset of the disease, it is recommended to visit the ENT department, where routine blood tests, coagulation tests and nasal endoscopy can be done to help determine the condition and make a clear diagnosis. In terms of treatment, most patients can choose medication, more commonly used is nasal spray medication, and some patients can also use saline to cleanse the nasal cavity, which requires regular review and observation of the effect.