Quick answer

What could blood in poo mean?

Blood in poo may appear bright red on the paper or in the bowl, or make stools dark and tar-like. Common causes include haemorrhoids (piles) and anal fissures, but bowel cancer can also cause bleeding — see a GP for any unexplained blood, change in bowel habit, or if you are over 40 with rectal bleeding.

Do not assume it is piles

Blood in poo — rectal bleeding — is common and often caused by benign conditions such as haemorrhoids (piles) or anal fissures. But bowel cancer can present with identical symptoms, especially with a change in bowel habit. Every episode of unexplained rectal bleeding deserves GP assessment — not self-diagnosis.

What blood may look like

Bright red blood:

  • on toilet paper after wiping
  • dripping into the toilet bowl
  • coating the outside of stool

Usually indicates bleeding from the lower bowel — anus, rectum, or lower colon. Common causes: piles, fissures, diverticular disease.

Dark red or black tar-like stools (melaena):

  • sticky, foul-smelling, black stools

Suggests bleeding from the upper gut — stomach or small intestine. Needs urgent medical assessment — call NHS 111 or go to A&E.

Blood mixed through stool:

  • maroon or dark blood throughout

May indicate bleeding from higher in the colon. Always needs investigation.

Common causes

Haemorrhoids (piles) — swollen blood vessels in or around the anus. Cause bright red bleeding, itching, and lumps. Very common.

Anal fissure — small tear in the anal lining. Causes bright red blood and sharp pain when passing stool.

Diverticular disease — pouches in the colon wall that can bleed.

Inflammatory bowel disease — Crohn’s disease and ulcerative colitis cause bleeding with diarrhoea and abdominal pain.

Polyps — growths on the bowel lining; some can become cancerous over time.

Bowel cancer — bleeding may be the only symptom, especially early on. Associated with change in bowel habit, weight loss, abdominal pain, or iron deficiency anaemia.

When to see a GP

See a GP for any unexplained blood in poo — even a single episode.

Book an urgent appointment if you have:

  • blood with a change in bowel habit lasting 3 weeks or more
  • unexplained weight loss
  • persistent abdominal pain
  • you are over 40 with rectal bleeding — do not assume piles without examination
  • iron deficiency anaemia on blood tests

Bowel cancer screening

The NHS sends FIT (faecal immunochemical test) kits to eligible adults to detect hidden blood in stool. A positive result needs follow-up — usually colonoscopy. Screening finds cancer early when treatment is most effective. Complete your kit when it arrives.

What a GP may do

  • examine the abdomen and possibly perform a rectal examination
  • arrange blood tests — full blood count, iron studies
  • refer for colonoscopy or flexible sigmoidoscopy if indicated
  • treat confirmed piles or fissures if no red flag features

Emergency bleeding

Call 999 or go to A&E for:

  • large-volume rectal bleeding
  • fainting or dizziness with bleeding
  • severe abdominal pain
  • black tar-like stools

Red flags alongside bleeding

Seek prompt assessment if bleeding comes with:

  • looser stools or going more often for 3+ weeks
  • feeling of incomplete emptying
  • unexplained weight loss
  • fatigue from anaemia
  • a lump in the abdomen or rectum

These features increase concern for bowel cancer regardless of age.

If you have been told you have piles

Even confirmed piles can coexist with other conditions. If bleeding continues despite pile treatment, or bowel habit changes, return to your GP for reassessment.

Common questions

What does blood in poo look like?
Bright red blood on toilet paper, dripping into the bowl, or coating the surface of stool usually comes from the anus or lower rectum. Dark red or black tar-like stools (melaena) suggest bleeding from higher in the stomach or intestine — this needs urgent assessment.
What are the most common causes?
Haemorrhoids (piles), anal fissures (small tears), diverticular disease, inflammatory bowel disease, polyps, and bowel cancer. Piles are common but should be diagnosed — not assumed — especially over 40.
Could blood in poo be bowel cancer?
Yes. Bowel cancer can cause rectal bleeding, often with a change in bowel habit — looser stools, going more often, or feeling the bowel is not fully empty. It is more common over 50 but can occur younger. Early diagnosis improves outcomes significantly.
What is bowel cancer screening?
In England, people aged 60 to 74 (expanding to 50) receive home faecal immunochemical test (FIT) kits every two years to detect hidden blood. A positive result needs follow-up colonoscopy — it does not mean cancer, but needs investigation.
When is rectal bleeding an emergency?
Large-volume bleeding, fainting, severe abdominal pain, or black tar-like stools need urgent hospital assessment. Moderate ongoing bleeding also needs same-day medical advice.

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