What are the causes of epistaxis?

Epistaxis, or a nosebleed, is when you lose blood from the tissue that lines the inside of your nose. The causes of epistaxis include trauma (i.e. blowing the nose too aggressively, a knock on the nose or anything that causes vessels to rupture), dry air/low humidity, mucosal irritation due to environmental irritants, using medication like aspirin and warfarin that retard coagulation of blood, repeated use of nasal sprays, inflammatory reaction due to allergies or infections (e.g. sinusitis, rhinitis, respiratory tract infections), systemic conditions such as hypertension, drugs such as cocaine, tumors, blood disorders (i.e. clotting factor deficiency), septal abnormality, and less common causes include vascular disorders, genetic disorders such as hereditary hemorrhagic telangiectasia [HHT], hemophilia, liver disease, vitamin deficiencies among others.