Rectal bleeding

What is rectal bleeding?

Rectal bleeding means blood coming from your back passage. You might spot it as a smear on toilet paper, a streak along your stool, a rosy tint to the toilet bowl water, or blood mixed right through your poo, and sometimes it's slow enough that you don't notice it at all. A single, small episode often settles by itself, but it's always worth getting checked to find out why it happened.

What are the common causes of rectal bleeding?

By far the most frequent causes are also the least serious:

• piles, meaning swollen veins around your bottom that tend to bleed after you've strained on the toilet
• a small split in the delicate skin around your anus (an anal fissure), usually from passing hard or large faeces.

Other possible causes include:

• diverticular disease, small pouches that form in the bowel wall and can bleed, often without any pain
• gastroenteritis or a bowel infection, usually alongside diarrhoea, cramps, and feeling sick
• inflammatory bowel disease, meaning conditions like Crohn's or ulcerative colitis, typically with ongoing bloody diarrhoea
• an anal fistula that connects a gland inside the anal canal to an opening on the skin near the anus
• angiodysplasia, fragile abnormal blood vessels that become more common as you get older
• medicines that thin the blood, such as warfarin, apixaban, or aspirin
• anal sex, including certain sexually transmitted infections
• bowel polyps, small growths that are usually harmless but occasionally develop into cancer
• rarely, bowel or rectal cancer itself.

Are there different types of rectal bleeding?

The colour and consistency of what you see gives a genuine clue as to whereabouts the bleeding started:

• A vivid red colour, whether on the paper, on the surface of your stool, or turning the toilet water pink, generally points to somewhere near the anus, such as piles or a fissure.
• Darker red blood mixed right through your stool suggests the source is a bit further up, in your colon, and can be linked to things like polyps or diverticular disease.
• Very dark, black, or tar-like stool with an unusually strong smell tends to mean bleeding higher up still, often in your stomach, and needs prompt attention.

How is rectal bleeding diagnosed?

Your GP will usually start by asking about the bleeding itself, how long it's lasted, its colour, whether it hurts to pass stool, and whether you've noticed any other changes like weight loss or altered bowel habits. Many appointments include a rectal examination, where a gloved, lubricated finger is used to feel for anything unusual. It's quick, and not something to feel embarrassed about.

Depending on what's found, you might have a stool sample tested, blood tests, or a referral for a closer look inside using a proctoscope, sigmoidoscope, or colonoscope. Which test you need depends on your age, your symptoms, and what your GP finds on examination.

How is rectal bleeding treated?

Treatment depends entirely on what's behind it. Piles and fissures often improve with simple self-care: eating more fibre, drinking plenty of fluids, avoiding straining, and having a warm bath, alongside pharmacy creams for comfort if needed. If these keep coming back, your GP might discuss further options such as injections or a minor procedure.

Where an infection is responsible, you may need antibiotics; inflammatory bowel disease is managed with specific medicines from a specialist; and polyps or other growths are usually removed during the same examination that finds them. Heavier or ongoing bleeding sometimes needs hospital-based treatment to stop it directly and address the underlying cause.

When should you see a doctor?

See a GP if you notice blood in your poo that lasts three weeks or more, if your stool has changed to looser, thinner, or more watery than usual for three weeks, if you're in significant pain around your bottom, if you have tummy pain or a lump, if you've felt unusually tired, or if you've lost weight without trying. Any blood in a child's poo is also worth a GP visit.

Bleeding from the back passage can occasionally be an early sign of bowel cancer, and catching this early makes a real difference to treatment, so please don't let embarrassment put you off getting checked.

Ring 111 or ask your practice for a same-day appointment if your stool has turned black or a deep red, or if you have diarrhoea with visible blood in it.

Call 999 or go to A&E if the bleeding won't stop, if there's a large amount of blood such as the toilet water turning red or visible clots, if you feel faint, dizzy, or confused, if you're in severe pain, or if heavy bleeding comes with fever or an inability to pass stool at all.