Is blood in my poo normal?

Written by: Dr Aathavan Loganayagam
Published:
Edited by: Laura Burgess

Bleeding from your back passage (anus) when you go to the toilet and pass faeces (poo) can occur for many different reasons. This is known as rectal bleeding. You should always have rectal bleeding checked out by a doctor as it could be a sign of something serious.


Seek urgent medical attention if the bleeding is very heavy, if you also have bad tummy pains, or if you have signs of shock like rapid, shallow breathing, dizziness, nausea or confusion.

Causes of rectal bleeding

There are lots of reasons for rectal bleeding to occur, including: 

  • Constipation
  • Haemorrhoids (also known as piles)
  • Anal fissure (a small tear in the opening of the anus) or fistula (a small channel that develops between the anus and skin)
  • Rectal trauma
  • Polyps
  • Stomach or duodenal ulcers
  • Infections of the bowel
  • Gastroenteritis
  • Conditions of the bowel, such as diverticular disease or colon cancer, Crohn’s disease or ulcerative colitis
  • Sexually transmitted infection.

What does the colour of the blood in my stool indicate?

The colour of your blood can indicate where in the gastrointestinal system the bleeding is coming from. For example, fresh, bright red blood can show the bleeding is coming from lower in the bowel, nearer to the back passage, which may be a sign of haemorrhoids, fissures or other localised conditions.

Bleeding in your large intestine (colon) may be fresh red or a darker red and mixed in with your faeces. One of the causes can be polyps, which are growths on the intestinal wall.

Polyps are usually harmless, but some types can turn into more serious conditions such as bowel cancer. Polyps, therefore, need to be further investigated and assessed by a healthcare professional.

Faeces that are black, like tar, and that have a very bad smell may suggest a problem higher up in the gastrointestinal system - for example, in the stomach or duodenum - such as a bleeding ulcer.

It is very important that any bleeding from the gastrointestinal system is checked by a healthcare professional. Further assessments and tests may be needed to establish the cause of the problem.

By Dr Aathavan Loganayagam
Gastroenterology

Dr Aathavan Loganayagam is a leading London gastroenterologist who trained in medicine at Guy’s, King's and St Thomas’ medical schools. He underwent rigorous structured specialty training in gastroenterology and general internal medicine in the well respected South London training programme.

Dr Loganayagam spent two years during postgraduate training as a research and endoscopy fellow at Guy’s and St Thomas’ Hospitals, London. His research was in the fields of pharmacogenetics, inflammatory bowel disease and gastrointestinal malignancy.

He has received many awards and grants for outstanding research work, including the prestigious NHS Innovation London Award. Dr Loganayagam has numerous publications in peer-reviewed journals on all aspects of gastroenterology. He is actively involved in clinical research.

Currently, Dr Loganayagam is the lead clinician for inflammatory bowel disease and nutrition at Queen Elizabeth Hospital, Woolwich. Diagnostic and advanced therapeutic endoscopy remains a major part of his clinical expertise, including assessment and treatment of inflammatory bowel disease, strictures, polyps and cancers.

Dr Loganayagam is an approachable doctor who takes pride in his communication skills with patients and he is keen to ensure that patients are fully informed and involved in all aspects of their care.

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