Reviewed by The Wellness Team. Last reviewed October 2026.
Seeing blood in your poo is frightening, but the most common causes are piles and small tears, both very treatable. Bright red blood on the paper or coating the stool usually comes from near the back passage. Blood mixed through the stool, darker blood or black tarry stools, or bleeding with a change in bowel habit, weight loss or tiredness should always be assessed promptly, because bowel cancer becomes more treatable the earlier it is found. Whatever the pattern, one short GP consultation can usually tell you how seriously to take it and what test settles it.
The common causes
Most rectal bleeding comes from benign causes:
- Piles (haemorrhoids): bright red blood, often on the paper or dripping after a bowel movement, sometimes with itching or a lump
- Anal fissure: a small tear that causes bright red blood with a sharp pain on passing a stool
- Constipation: hard stools that trigger both piles and fissures
- Gut infections: loose stools with blood and mucus, usually after a bout of diarrhoea
- Inflammatory bowel disease: blood with mucus, urgency and crampy tummy pain, often in younger adults
- Bowel polyps and bowel cancer: often painless bleeding mixed into the stool, sometimes the only early sign
What the pattern tells you
Bright red blood, separate from the stool, points towards piles or a fissure. Blood mixed through the stool, blood with mucus, or very dark red blood suggests the bleeding is higher up in the bowel. Black, sticky, tar-like stools with a distinctive smell mean bleeding from the stomach or upper gut and need urgent assessment.
The pattern narrows things down but it cannot exclude serious causes on its own. That is what examination and testing are for.
Symptoms that mean you should be seen promptly
Book an assessment soon rather than watching and waiting if you have:
- Bleeding that keeps happening or lasts more than a few days
- A change in your normal bowel habit lasting three weeks or more, especially looser or more frequent stools
- Unexplained weight loss, tiredness or looking pale
- A family history of bowel cancer, particularly in a close relative diagnosed young
- Any rectal bleeding over the age of 40 without obvious piles
NICE guideline NG12 sets out which combinations of symptoms need urgent investigation for possible cancer, and your GP uses those thresholds to decide what happens next. Seek urgent same-day care for black tarry stools, large amounts of blood, dizziness or feeling faint.
How a GP works it out
Assessment starts with the pattern: colour, amount, how long, and what comes with it. Examination may include feeling the tummy and, where appropriate, a gentle rectal examination. From there, the two tests that settle most cases are a stool test called FIT (a faecal immunochemical test, which detects hidden blood in the stool and guides referral decisions in primary care under NICE guidance) and blood tests to check for anaemia and inflammation. Where the picture or the FIT result needs it, your GP arranges referral for a camera test of the bowel, and private pathways mean that happens in days rather than months.
What an online GP can do today
A phone consultation costs £59, video £150, or £220 in person at 10 Portman Square, Marylebone. Your GP can assess the pattern, examine you if you come in person, arrange a FIT stool test and blood tests, prescribe treatment for piles or fissures, and fast-track any referral that is needed, all from one appointment. Message us on WhatsApp at https://wa.me/447961280835 and we will find you a time today.
Frequently asked questions
Is blood in poo always cancer?
No, and usually it is not. Piles and fissures account for most rectal bleeding, especially bright red blood in younger people. The point of assessment is not to assume the worst; it is to be sure, because certainty is quick to get and reassurance is better than wondering.
Can piles really cause that much blood?
Yes. Piles can bleed impressively, dripping into the bowl after a bowel movement, and still be harmless. But nobody can tell piles from something more serious by the amount of blood alone, which is why recurring bleeding always deserves a proper look.
Should I go to A&E for blood in my poo?
Only if you are passing large amounts of blood, have black tarry stools with dizziness or fainting, or have severe tummy pain. Otherwise a same-day GP consultation is faster and more useful, and your GP will direct you to urgent care if the picture needs it.
It happened once and stopped. Does it still matter?
A single small smear on the paper after a hard stool is most likely a fissure and can reasonably be watched for a few days. Anything that recurs, lasts more than a few days, or comes with other symptoms should be assessed, particularly if you are over 40.
Sources: NICE guideline NG12, Suspected cancer: recognition and referral; NICE guidance on quantitative faecal immunochemical testing (FIT) in primary care; NICE Clinical Knowledge Summaries, Rectal bleeding.
Reviewed by The Wellness Team