Some of the most common causes include trauma from nose picking, blunt trauma (such as a motor vehicle accident), or insertion of a foreign object (more likely in children). Relative humidity (including centrally heated buildings), respiratory tract infections, chronic sinusitis, rhinitis or environmental irritants can cause inflammation and thinning of the tissue in the nose, leading to a greater likelihood of bleeding from the nose.Most causes of nose bleeding are self-limiting and do not require medical attention. However, if nosebleeds are recurrent or do not respond to home therapies, an underlying cause may need to be investigated. Some rarer causes are listed below:Coagulopathy

Thrombocytopenia (thrombotic thrombocytopenic purpura, idiopathic thrombocytopenic purpura)
Von Willebrands disease
Hemophilia
Leukemia
HIV
Chronic liver disease—cirrhosis causes deficiency of factor II, VII, IX,& XDietary

Sulfur dioxide (sulphur dioxide) E220 (as a food preservative used particularly in wines, dried fruits, etc. ) Sulphites as food preservatives
Salicylates naturally occurring in some fruits and vegetablesInflammatory

Granulomatosis with polyangiitis
Systemic lupus erythematosusMedications/Drugs

Anticoagulation (warfarin, heparin, aspirin, etc.) Insufflated drugs (particularly cocaine)
Nasal sprays (particularly prolonged or improper use of nasal steroids)Neoplastic

Squamous cell carcinoma
Adenoid cystic carcinoma
Melanoma
Nasopharyngeal carcinoma
Nasopharyngeal angiofibroma
Nosebleeds can be a sign of cancer in the sinus area, which is rare, or tumors starting at the base of the brain, such as meningioma. Due to the sensitive location, nosebleeds caused by tumors are typically associated with other symptoms, such as hearing or vision problems.Traumatic

Anatomical deformities (e.g.
septal spurs)
Blunt trauma (usually a sharp blow to the face such as a punch, sometimes accompanying a nasal fracture)
Foreign bodies (such as fingers during nose-picking)
Digital trauma
Middle ear barotrauma (such as from descent in aircraft or ascent in scuba diving)
Nasal bone fracture
Septal fracture/perforation
Surgery (e.g. septoplasty and functional endoscopic sinus surgery)
Nasal bleeds may be due to fracture of facial bones namely maxilla and zygoma.Vascular

Hereditary hemorrhagic telangiectasia (Osler–Weber–Rendu disease)
Angioma
Aneurysm of the carotid artery

Pathophysiology
The nasal mucosa contains a rich blood supply that can be easily ruptured and cause bleeding. Rupture may be spontaneous or initiated by trauma. Nosebleeds are reported in up to 60% of the population with peak incidences in those under the age of ten and over the age of 50 and appear to occur in males more than females. An increase in blood pressure (e.g. due to general hypertension) tends to increase the duration of spontaneous epistaxis. Anticoagulant medication and disorders of blood clotting can promote and prolong bleeding. Spontaneous epistaxis is more common in the elderly as the nasal mucosa (lining) becomes dry and thin and blood pressure tends to be higher. The elderly are also more prone to prolonged nosebleeds as their blood vessels are less able to constrict and control the bleeding. The vast majority of nosebleeds occur in the front anterior (front) part of the nose from the nasal septum. This area is richly endowed with blood vessels (Kiesselbachs plexus). This region is also known as Littles area.