Nosebleeds can be caused by a variety of reasons, including malignant tumors of the nasal cavity, blood system diseases such as leukemia, and other major diseases, as well as dry weather, nose picking and other bad habits. You can’t judge whether nosebleed is a precursor of big disease by nosebleed, you need to go to the hospital to get a clear diagnosis. 1. Maxillary sinus cancer: it is a kind of malignant tumor occurring in the mucous membrane of maxillary sinus, which can lead to nasal obstruction, nosebleed, displacement of eyeballs, pain and other discomfort symptoms. 2. Sieve sinus cancer: also known as sieve sinus malignant tumor, it is a malignant tumor occurring in sieve sinus of the nose, the cause of which is still unclear, and it is considered to be caused by the interaction of long-term chronic stimulation, exposure to carcinogens, trauma and other factors. It can lead to nasal congestion, bloody snot, headache and other uncomfortable symptoms, and the rate of progress is relatively fast, most patients are already in the late stage when they visit the doctor. 3. Leukemia: it is a kind of malignant clonal disease of hematopoietic stem progenitor cells, which is mainly caused by abnormalities of self-proliferation, differentiation and apoptosis of leukemia cells, and can lead to anemia, bleeding, infection and other uncomfortable symptoms, and clinically there will be nosebleeds. Nosebleed is not only a symptom of some big diseases, but also may be caused by some daily bad factors. If the climate is dry, the nasal mucosa is dry and dehydrated, which causes the capillaries in the nasal cavity to rupture and bleed, triggering nosebleeds; secondly, some patients like to pick their noses, and accidentally picking through the mucosa of the nasal cavity can also cause nosebleeds. Once the nose bleeds, need to actively go to the hospital, clear cause and diagnosis, under the guidance of physicians standardized treatment.