Rectal bleeding can be very alarming. Sometimes you might not even notice it until you see blood on toilet paper or in the water of the toilet bowl. 

Blood in bowel movements may be a symptom of several medical conditions, and in some instances, it may be caused by a minor condition and can be treated easily or it may go away after a while. 

That being said, some serious gastrointestinal conditions may also cause rectal bleeding. If a patient experiences any other symptoms along with bleeding, they may need to seek medical attention.

What can cause blood in bowel movements?

These are some gastrointestinal conditions that may cause rectal bleeding:


These are swollen veins found in the rectum or the anus. Usually, haemorrhoids are not serious, but they can sometimes bleed when passing stool.

Anal fissures

Anal fissures are breaks in the skin around the anus, which may cause pain and bleeding when passing stools. Fissures may go away without treatment.

Hard stools

Sometimes, the stool becomes too hard and when they move through the rectum, it can cause scratches and lead to bleeding when passing stools.

These are some less common, but more serious causes of blood in stool:

Colon cancer

A type of cancer that affects the large intestine, colon cancer is a serious condition that progresses slowly and needs to be treated as early as possible.

It may start as small non-cancerous clumps of cells known as polyps, and over time, become cancerous.

Inflammatory bowel disease (IBD)

IBD is an umbrella term for two medical conditions; Crohn’s disease and ulcerative colitis.

Crohn’s disease may cause inflammation in any part of the gastrointestinal tract but usually affects the small intestine. Ulcerative colitis causes inflammation too, but only in the large intestine.

If you experience rectal bleeding or blood in stools, consult a gastrointestinal specialist, even if you don’t have any other symptoms.

When does blood in bowel movements become a medical emergency?

If the bleeding is accompanied by other symptoms, it may be a sign of a more serious underlying health condition. 

If you notice the following symptoms, consult your gastrointestinal doctor as soon as possible.

  • Clammy skin

  • Rapid breathing

  • High fever

  • Pale complexion

  • Sharp abdominal pain

  • Nausea

  • Black, tarry looking stools

  • Sudden changes in bowel movements

Speak to an experienced gastroenterologist

Dr Suhirdan Vivekanandarajah is a gastroenterologist based in Sydney who specialises in the diagnosis and treatment of a wide range of gastrointestinal conditions.

If you are experiencing symptoms of any of the medical conditions mentioned above, speak to Dr Vivekanandarajah for treatment and support.

Consult Dr Suhirdan at these locations 

St Vincent's Clinic

Meet Dr Suhirdan Vivekanandarajah

Interventional Gastroenterologist and Hepatologist

Bsc (Med) | M.B.B.S. (Hons) | FRACP


Does black stool always indicate internal bleeding?

What does bright red blood in stool mean?

How can the source of blood in bowel movements be found?

Get in touch for more support, treatment and information on gastrointestinal health.

Dr Suhirdan's services are only available to patients in Australia.

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