Blood in the stool

Category: Digestive & Abdomen · All digestive symptoms

What it can feel like

Blood in the stool means seeing red blood on the paper, in the pan or mixed with the stool, or passing black, tarry stools (which suggests bleeding higher up). Any rectal bleeding deserves assessment — most causes are benign, but bowel cancer is on the list and is far more treatable when found early.

Possible causes

A symptom can have many causes, and most are not serious. The lists below group conditions this symptom can be associated with — common causes first. They are possibilities to discuss with a clinician, not a diagnosis.

Common causes

Blood in the stool can be associated with piles (haemorrhoids), a small tear of the anus, diverticular disease, infections and inflammation of the bowel such as colitis or proctitis.

Other possible causes

Bleeding can also be associated with bowel polyps and bowel cancer, and black tarry stools can come from ulcers or bleeding in the stomach. Blood-thinning medicines can make any of these bleed more.

Red flags — when to seek help promptly

Heavy bleeding, or bleeding with dizziness, faintness or a racing pulse
Black, tarry stools
Bleeding with a persistent change in bowel habit or weight loss
Bleeding in someone over 50 that has not been assessed
Bleeding with severe abdominal pain

What a clinician may do

A clinician will ask about the amount, colour and pattern, examine your abdomen and usually the rectum, and check a blood count. A stool test for hidden blood (FIT) is often used to prioritise, and referral for a camera examination of the bowel (colonoscopy) is the usual next step when bleeding is unexplained.

Watch: related videos

Examination and clinical videos from the MedicalVideos.com library relevant to this symptom. Some clinical footage is graphic — that is the nature of a medical video library.

▶ WatchRectal bleedingWatch on MedicalVideos.com ▶ WatchTesting for occult blood in the stoolWatch on MedicalVideos.com

Related guides on MedicalVideos.com

Frequently asked questions

It's just a little blood on the paper — why must I report it?

Because the amount does not reliably separate piles from polyps or cancer, and because early bowel cancer often bleeds only slightly. Reporting it gets you a blood count, a stool test and, where indicated, a camera test — most people are reassured, and the minority who need treatment get it early.

What does black stool mean?

Black, tarry, smelly stools usually mean blood has been digested on its way through — pointing to bleeding in the stomach or upper bowel. Iron tablets and bismuth can also darken stools, but a new black stool should be reported the same day.

Related symptoms — Digestive & Abdomen

Abdominal pain Black stools Bloating Change in bowel habit Constipation Diarrhoea

Browse the B section of the A–Z list or return to the Symptoms A–Z hub.

Please note: This page is educational information about a symptom. A symptom alone cannot diagnose any condition, and the causes listed here are possibilities, not a diagnosis. If you are worried about a symptom — especially one that is new, severe, getting worse or not going away — please see your own clinician, who can examine you and arrange tests. In an emergency, call your local emergency number.