1 Trauma In the process of some trauma, such as digging your nose too deep, sneezing or blowing your nose, great pressure forces the capillaries in the nasal cavity to rupture, leading to nosebleeds. Generally speaking, only one side is compressed, and the number of blood vessel ruptures is more.

2 Air pressure injury When the air pressure difference between the nasal cavity and the sinus is too large, such as pilots, divers, tunnel workers, etc., it can cause mucosal blood vessels in the sinus to dilate or rupture and bleed, and even the same person, the tolerance of the left and right nasal capillaries will be different, resulting in unilateral epistaxis.

3 Deviation of nasal septum The mucosal tension in some parts of patients with nasal septum deviation is large and thin, which is often directly stimulated by airflow and dust, and the mucosa is dry and crusted, which is easy to erosion. In addition, the soft tissue of nasal septum is rich in blood supply, which is more prone to unilateral epistaxis.

4 Inflammation When the nasal cavity is infected, the nasal mucosa will become thinner and even fester due to inflammation, while general inflammation is more common on one side, which easily leads to unilateral nosebleed.