Bilateral nose bleeding may be caused by nasal vasodilatation, but it may also be caused by trauma, inflammation, nasal deformity or certain systemic factors. 1. Bleeding caused by nasal vasodilatation may be due to hereditary hemorrhagic capillary dilatation: recurrent nosebleeds, and for the first symptom, often with a family history of easy bleeding, a dominant hereditary disease. 2. Trauma: nasal bleeding can occur when sinus wall, nasal septum, nasal bone fracture leads to nasal mucous membrane and blood vessel injury, surgical trauma and other injuries to the mucous membrane of the nasal cavity can also cause nasal bleeding. 3. Inflammation: acute rhinosinusitis, dry rhinitis, atrophic rhinitis and other infectious inflammation of the nasal mucosa can cause nasal mucosal bleeding. 4. Nasal deformity: deviated nasal septum, nasal septum erosion, ulceration or perforation can cause nosebleed. 5. Systemic factors: cardiovascular diseases such as hypertension, vascular sclerosis, heart failure, etc., blood diseases such as hemophilia and leukemia, etc., malnutrition or vitamin deficiencies may lead to nosebleeds. There are many causes of bilateral nosebleeds, if the bleeding is repeated and the symptoms are serious, you should go to the hospital for detailed examination.