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Health condition

Anal bleeding, from a common pile to the red flags you should not ignore.

Most rectal bleeding is a haemorrhoid or a fissure. But the pattern of the blood, your age and any change in bowel habit decide whether you need a colonoscopy.

A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against NICE, BSG and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK guidance including FIT testing, NICE 2-week wait criteria and colonoscopy pathways.

Key facts

Anal bleeding at a glance.

The essentials, in plain English. What causes it, what to notice and how UK clinicians decide who needs a colonoscopy.

  • What it is

    Blood passed from the anus or rectum. Most often bright red on the paper or coating the stool, sometimes darker and mixed in.

  • Most common cause

    Haemorrhoids. Bright red bleeding on wiping or dripping into the pan, usually without pain and not mixed through the stool.

  • Painful bleeding

    An anal fissure. Sharp pain during and after defecation with fresh blood on the paper is the classic pattern.

  • Red flag pattern

    Dark blood mixed through stool with a change in bowel habit, weight loss or iron-deficiency anaemia needs urgent colonoscopy.

  • FIT testing

    Quantitative faecal immunochemical testing is now the front-door investigation in primary care for suspected colorectal cancer.

  • Gold-standard test

    Colonoscopy visualises the whole colon and takes biopsies. It is the definitive investigation for most adults with rectal bleeding.

Why this guide matters

Common, treatable, but never to be assumed.

Rectal bleeding is one of the top reasons people put off going to the GP. The three points below shape everything else on this page.

  • The pattern tells you a lot

    Bright red on the paper is very different from dark blood mixed through stool. The colour, timing and pain pattern narrow the diagnosis before any test.

  • Never assume it is just piles

    Haemorrhoids are common, but so is colorectal cancer. New bleeding, a change in bowel habit or weight loss deserves fresh investigation, even if you know you have piles.

  • FIT and colonoscopy save lives

    Quantitative FIT triages primary-care referrals and colonoscopy remains the gold standard. Early diagnosis of colorectal cancer changes outcomes dramatically.

How the diagnosis is made

From first symptom to a clear plan.

The steps a UK GP or colorectal team will normally follow, in order, so you know what to expect and why.

  1. 01

    Assessing

    History and pattern of bleeding

    Colour, amount, whether the blood is on the paper, coating stool or mixed through it, pain, bowel habit, weight loss and family history of colorectal cancer or IBD.

  2. 02

    Assessing

    Abdominal and PR exam

    A digital rectal examination looks for masses, tenderness and prolapsed haemorrhoids. Proctoscopy visualises the anal canal and lower rectum in clinic.

  3. 03

    Assessing

    Baseline bloods

    Full blood count for anaemia, ferritin and iron studies, urea and electrolytes, liver function and CRP to screen for inflammation.

  4. 04

    Confirming

    FIT and faecal calprotectin

    Quantitative FIT triages colorectal cancer risk. Faecal calprotectin points to inflammatory bowel disease when diarrhoea and urgency are present.

  5. 05

    Confirming

    NICE 2-week wait referral

    Age 50 and over with rectal bleeding for six weeks, age 60 and over with anaemia, or an abdominal or rectal mass all trigger urgent suspected-cancer referral.

  6. 06

    Investigating

    Colonoscopy or flexible sigmoidoscopy

    Colonoscopy is the gold standard for adults over 45 or anyone with red flags. Flexible sigmoidoscopy suits younger patients with no alarm features.

  7. 07

    Investigating

    Cross-sectional and vascular imaging

    CT abdomen and pelvis for suspected diverticular disease or malignancy. CT angiography or a bleeding scan for brisk, active haemorrhage. Capsule endoscopy for obscure small-bowel bleeding.

Typical timeline: from GP visit to colonoscopy within two weeks when NICE criteria are met.

Symptoms

What the pattern of bleeding tells us.

Colour, timing, pain and any change in bowel habit are the clues that turn a symptom into a diagnosis.

  • Bright red on the paper

    Blood on wiping or dripping into the pan, not mixed with stool. Most often haemorrhoids or an anal fissure.

  • Pain during defecation

    Sharp, tearing pain with a small streak of fresh blood is the classic anal fissure pattern.

  • Bloody diarrhoea and urgency

    Loose stool with blood, urgency, tenesmus and mucus suggest inflammatory bowel disease or infective colitis.

  • Dark blood mixed with stool

    Altered blood mixed through the stool points to a higher lesion in the colon and needs colonoscopy.

  • Change in bowel habit

    A new, persistent change in stool frequency or calibre with bleeding is a red flag for colorectal cancer.

  • Painless brisk bleeding

    A larger volume of dark or maroon blood in an older adult, often without warning, is typical of diverticular haemorrhage.

  • Chronic iron-deficiency anaemia

    Tiredness, breathlessness and pale skin with a low ferritin can be the only sign of a slowly bleeding cancer or angiodysplasia.

  • Red flag - weight loss and mass

    Unintentional weight loss, an abdominal or rectal mass, or family history of colorectal cancer needs urgent referral.

Treatment

How anal bleeding is treated in the UK.

Every plan begins with the underlying cause. From lifestyle and topical creams for haemorrhoids and fissures through to surgery and biologics for IBD and cancer.

  • Treat the underlying cause

    Every plan starts with a diagnosis. The right treatment for haemorrhoids is not the right treatment for a fissure, IBD, diverticular disease or cancer.

  • Haemorrhoids - conservative

    Increased dietary fibre, adequate fluids, sitz baths and short-course topical creams settle most first and second-degree haemorrhoids.

  • Haemorrhoids - procedures

    Rubber-band ligation in clinic for stubborn internal haemorrhoids. Haemorrhoidectomy or stapled procedures for larger, symptomatic disease.

  • Anal fissure - medical

    Topical GTN 0.2 to 0.4 per cent or diltiazem 2 per cent ointment relaxes the internal sphincter. Botulinum toxin is an option before surgery.

  • Anal fissure - surgical

    Lateral internal sphincterotomy for chronic fissures that fail medical therapy. Very effective, with a small risk of continence change.

  • Inflammatory bowel disease

    A stepped ladder from 5-ASAs and steroids to immunomodulators and biologics. Surgery for refractory disease or complications.

  • Diverticular bleeding

    Most settle with supportive care and transfusion. Selective mesenteric embolisation or endoscopic therapy for persistent bleeding.

  • Colorectal cancer

    Surgical resection is the mainstay, with adjuvant chemotherapy or radiotherapy chosen by stage and MDT decision. Early detection changes outcomes.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or colorectal specialist knows your history and can tell you which parts apply to you. If you have any red flag, do not wait.

  • NICE. Suspected cancer: recognition and referral (NG12).

  • NICE. Quantitative faecal immunochemical testing to guide colorectal cancer pathway referral (DG56).

  • British Society of Gastroenterology. Guidelines on the management of rectal bleeding.

  • Association of Coloproctology of Great Britain and Ireland (ACPGBI). Position statements on haemorrhoids and anal fissure.

Red flags

When rectal bleeding needs urgent attention.

Most anal bleeding is not sinister. These are the situations that are, and where prompt investigation matters most.

  • Haemodynamic instability

    Dizziness, fainting, a fast pulse or a drop in blood pressure with brisk rectal bleeding is a 999 emergency. Do not drive yourself.

  • Large-volume fresh bleeding

    Passing clots or filling the pan with blood needs same-day hospital assessment for resuscitation, transfusion and endoscopy.

  • Weight loss with bleeding

    Unintentional weight loss combined with a change in bowel habit and rectal bleeding is a red flag for colorectal cancer.

  • Iron-deficiency anaemia

    A low ferritin with any rectal bleeding needs urgent investigation. It is often the first sign of a slowly bleeding lesion.

  • Abdominal or rectal mass

    A palpable mass on abdominal examination or PR examination triggers a 2-week wait suspected-cancer referral.

  • Age 50 and over, bleeding 6 weeks

    NICE NG12 sets this as a trigger for an urgent suspected colorectal cancer pathway.

  • Change in bowel habit

    A new, persistent change to looser or more frequent stools in an adult with bleeding warrants prompt colonoscopy.

  • Family history of bowel cancer

    A first-degree relative with colorectal cancer, or a known Lynch or FAP background, lowers the threshold for early investigation.

  • Immunocompromised patient

    Consider CMV colitis and opportunistic infection. Investigate early rather than assuming haemorrhoids.

Living with it

A common problem, with clear next steps.

Four things that make the biggest difference day to day. Feed the bowel well, avoid straining, track the pattern and act on any change.

A quiet reminder

Do not wait for embarrassment to cost you time.

Colorectal teams see rectal bleeding every day. Getting it looked at is the surest way to stop worrying and start treating it.

  1. 01 Fibre

    Feed your bowel well

    A high-fibre diet with plenty of fluids softens stool, cuts straining and reduces haemorrhoid and fissure symptoms.

  2. 02 Habit

    Do not linger on the toilet

    Long sits and heavy straining raise anal pressure. Answer the call, do the job and get up.

  3. 03 Track

    Note the pattern

    Colour, timing, pain and any change in bowel habit are the details your GP or specialist will want to hear.

  4. 04 Escalate

    Never assume it is haemorrhoids

    Even with known piles, new bleeding, a change in habit or weight loss deserves a fresh look. Ask for a colonoscopy if in doubt.

Frequently asked

Everything we get asked about rectal bleeding.

Quick answers on haemorrhoids, fissures, FIT testing, colonoscopy and IBD.

  • What is the most common cause of anal bleeding?

    Haemorrhoids are by far the most common cause. The typical pattern is bright red blood on the paper or dripping into the pan, not mixed through the stool and usually without pain.

  • When is anal bleeding an emergency?

    Call 999 or go to A&E if you feel dizzy or faint, notice a fast heartbeat, pass large volumes of blood or clots, or have severe abdominal pain. Any signs of shock with rectal bleeding are an emergency.

  • Does painful bleeding mean it is a fissure?

    Usually. Sharp, tearing pain during and after defecation with a streak of fresh blood is the classic anal fissure pattern. Chronic fissures can be treated with GTN or diltiazem ointment and, if needed, surgery.

  • When do I need a colonoscopy?

    NICE recommends urgent colonoscopy for adults aged 50 and over with rectal bleeding for six weeks, anyone aged 60 and over with anaemia, an abdominal or rectal mass, unexplained iron-deficiency anaemia, or a change in bowel habit with bleeding.

  • What is FIT testing and when is it used?

    Quantitative faecal immunochemical testing measures small amounts of blood in stool. In UK primary care it is used to triage suspected colorectal cancer referrals. A raised FIT with any bleeding usually prompts colonoscopy.

  • Can inflammatory bowel disease cause rectal bleeding?

    Yes. Ulcerative colitis and Crohn’s disease typically cause bloody diarrhoea with urgency, tenesmus and mucus. Faecal calprotectin, colonoscopy and biopsy make the diagnosis, and treatment ranges from 5-ASAs through to biologics and surgery.

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