Editing Nosebleed (section)

== Cause ==
[[File:Boxing children - bloody nose.jpg|thumb|right|350px|Two children [[boxing]], the one on the right having a nosebleed due to a punch to the face, in [[Vecsés]], [[Hungary]] in November 2006]]
Nosebleeds can occur due to a variety of reasons. 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).<ref name=Kell2014 /> Low [[relative humidity]] (such as in centrally heated buildings), [[respiratory tract infection]]s, [[chronic sinusitis]], [[rhinitis]] or environmental [[Irritant (biology)|irritant]]s can cause inflammation and thinning of the tissue in the nose, leading to a greater likelihood of bleeding from the nose.<ref name=Kell2014/>

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:<ref name=AFP2005/><ref name=Kell2014 /><ref name=":1">{{Cite journal|last1=Svider|first1=Peter|last2=Arianpour|first2=Khashayar|last3=Mutchnick|first3=Sean|date=June 2018|title=Management of Epistaxis in Children and Adolescents|journal=Pediatric Clinics of North America|volume=65|issue=3|pages=607–621|doi=10.1016/j.pcl.2018.02.007|pmid=29803286|s2cid=44125103|issn=0031-3955}}</ref>

'''Coagulopathy'''
* [[Thrombocytopenia]] ([[thrombotic thrombocytopenic purpura]], [[idiopathic thrombocytopenic purpura]])
* [[Von Willebrand's disease]]
* [[Hemophilia]]
* [[Leukemia]]
* [[HIV]]
* [[Chronic liver disease]]—cirrhosis causes deficiency of factor II, VII, IX,& X

'''Dietary'''
* [[Sulfur dioxide]] (sulphur dioxide) E220 (as a [[food preservative]] used particularly in wines and dried fruits)
* [[Sulphites]] as [[food preservatives]]
* [[Salicylates]] naturally occurring in some fruits and vegetables

'''Inflammatory'''
* [[Granulomatosis with polyangiitis]]
* [[Systemic lupus erythematosus]]

'''Medications/Drugs'''
* [[Anticoagulation]] ([[warfarin]], [[heparin]], [[aspirin]], etc.)
* [[Insufflation (medicine)|Insufflated]] drugs (particularly [[cocaine]])
* [[Nasal spray]]s (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.<ref>{{Cite web|date=2020-11-19|title=Nosebleeds & Headaches: Do You Have Brain Cancer?|url=https://ana-neurosurgery.com/symptoms-brain-tumor/|access-date=2020-12-14|website=Advanced Neurosurgery Associates|language=en-US}}</ref>

'''Traumatic'''
* [[Deformity|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 body|Foreign bodies]] (such as fingers during [[nose-picking]])
* Digital trauma ([[nose picking]])
* [[Middle ear]] [[barotrauma]] (such as from descent in aircraft or ascent in scuba diving)
* [[Nasal bone]] fracture
* Septal fracture/perforation
* Intranasal [[tumor]]s (''e.g.'' [[Nasopharyngeal carcinoma]] or [[nasopharyngeal angiofibroma]])
* [[Nasal cannula]] O<sub>2</sub> (tending to dry the [[olfactory mucosa]])
* [[Nasal spray]]s (particularly prolonged or improper use of nasal steroids)
* [[Surgery]] (''e.g.'' [[septoplasty]] and [[functional endoscopic sinus surgery]])
* [[Leech]] infestation<ref>{{cite journal |author=Yueng-Hsiang Chu & Jih-Chin Lee |url=http://content.nejm.org/cgi/content/full/361/9/e14 |title=Unilateral Epistaxis |journal=[[New England Journal of Medicine]] |year=2009 |volume=361 |pages=e14 |pmid=19710479 |doi=10.1056/NEJMicm0807268 |issue=9|url-access=subscription }}</ref>
* 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