Causes of a nosebleed 

Nosebleeds can start just inside your nostrils (anterior) or at the back of your nose (posterior).

Anterior nosebleeds

An anterior nosebleed comes from the wall between the two nose channels (the lower septum), just inside your nose. This part of the nose, sometimes known as Little's area, contains many delicate blood vessels, which can be easily damaged.

The cause of anterior nosebleeds is sometimes unknown, but they can be caused by a number of things, including:

  • picking your nose, particularly if you scratch the inside of your nose with a sharp fingernail
  • blowing your nose very hard
  • a minor injury to your nose
  • a crooked nose that's either present from birth (congenital) or the result of an injury (a deviated septum)
  • cold or flu (influenza)
  • sinusitis – an infection of the small, air-filled cavities inside your cheekbones and forehead
  • a blocked or stuffy nose often caused by an infection
  • a dry nose caused by dry air in a hot climate or heated indoor air
  • hay fever or other allergies
  • high altitude
  • excessive use of nasal decongestants
  • use of illegal drugs that are snorted – such as cocaine

Anterior nosebleeds are more common in children and are easily treated at home. Read more about treating nosebleeds.

Posterior nosebleeds

Posterior nosebleeds can be more serious than anterior nosebleeds. They are more common in adults than children. In this type of nosebleed, bleeding is heavier and comes from the back of your nose. Medical attention may be required.

During a posterior nosebleed, bleeding originates from branches of arteries that supply blood to the space inside your nose between the roof of your mouth and your brain (nasal cavity).

If your nosebleed is the result of a blow to your head, or a fall, seek medical attention because your nose may be broken. 

Other possible causes of posterior nosebleeds include:

  • recent nasal surgery
  • high blood pressure (hypertension)
  • hardened arteries (from fat, cholesterol or other substances that build up in your arteries)
  • exposure to irritating chemicals
  • a tumour in the nasal cavity
  • certain medicines – such as aspirin, medicines for arthritis and blood-thinning medicines (anticoagulants), such as warfarin and heparin

In some cases, nosebleeds can be a symptom of another condition, such as:

  • a blood clotting abnormality – such as haemophilia (an inherited condition affecting the blood’s ability to clot) or von Willebrand disease (an inherited disorder that causes bleeding and bruising)
  • leukaemia (although this is rare and you're likely to have other symptoms as well)
  • hereditary haemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber disease (an inherited condition that causes abnormalities in the blood vessels) - thought to affect between one in 5,000 and one in 10,000 people.

Page last reviewed: 31/05/2013

Next review due: 31/05/2015