Piles (Haemorrhoids) - Causes

What causes piles?

The lining of the back passage (anal canal) contains many blood vessels (veins). There seem to be certain changes in the veins within the lining of the back passage that cause the pile(s) to develop. The lining of the back passage and the veins become much larger and this can then cause a swelling and develop into a pile.

However, we don't know exactly what causes a pile. Some piles seem to develop for no apparent reason. It is thought that there is an increased pressure in and around the opening of the back passage (anus). This is probably a major factor in causing haemorrhoids in many cases. If you delay going to the toilet and need to strain when on the toilet then this can increase the pressure and so makes it more likely that a pile will develop.

About half of everyone in the UK develop one or more piles at some stage of their life.

What makes piles more likely?

There are certain situations that increase the chance of piles developing:

  • Constipation, passing large stools (faeces), and straining at the toilet. These increase the pressure in and around the veins in the anus and seem to be a common reason for piles to develop.
  • Being overweight. This increases your risk of developing piles.
  • Pregnancy. Piles are common during pregnancy. This is probably due to pressure effects of the baby lying above the rectum and anus, and also the affect that the change in hormones during pregnancy can have on the veins. Piles occurring during pregnancy often go away after the birth of the child.
  • Ageing. The tissues in the lining of the anus may become less supportive as we become older.
  • Hereditary factors. Some people may inherit a weakness of the wall of the veins in the anal region.
  • Other possible causes of piles include heavy lifting or a persistent (chronic) cough.

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Author:
Dr Colin Tidy
Peer Reviewer:
Dr Laurence Knott
Document ID:
4259 (v44)
Last Checked:
24 January 2017
Next Review:
24 January 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.