Bleeding from the anus

If you or a family member ever has bleeding from your anus (back passage or bottom), it’s important for you to see your doctor as soon as possible.

Anal bleeding can be a sign of many different problems. Some causes can be serious, which is why it should be checked out by your doctor.


Bright red blood may be seen only on toilet paper or in the toilet bowl after a bowel movement – not mixed freely with the bowel motion. This type of bleeding is usually caused by haemorrhoids (piles) or anal fissure.

  • A haemorrhoid is a swollen vein inside the anus.
  • A fissure is a split in the lining of the anus.
  • Both can be caused by constipation, and may cause difficult and painful bowel movements.

Blood mixed into the bowel movement usually means trouble further up from the anus: it may indicate an inflamed rectum or colon (large intestine or bowel). This type of bleeding can be caused by a serious condition, and you may have other symptoms as well.

Other symptoms:

  • sharp anal pain
  • mucus and pus in the bowel motions
  • constipation
  • abdominal pain
  • cramping
  • fever
  • diarrhoea
  • tiredness and being unusually pale – which may be a sign of anaemia (low blood count).

Blood mixed into the bowel motion may also indicate bowel cancer. Bowel cancer is the second leading cause of cancer death in New Zealand. Polyps may be found before the cancer develops. Polyps are small growths from the inner lining of the colon. They may cause minor bleeding.

Maroon or black blood is usually caused by bleeding higher in the gut.

  • Bleeding ulcers in the stomach or high in the small intestine cause black or tarry bowel motions.
  • Overuse of alcohol, aspirin or other anti-inflammatory medication can cause bleeding higher in the gut.
  • Iron pills cause black bowel motions but don’t cause bleeding.

When to see your doctor

If you notice either bright red or black/tarry anal bleeding, see your doctor as soon as possible. If your bleeding is non-stop or in large amounts, go to the emergency department immediately.

You may need tests to find the cause of the bleeding. These could include X-rays or endoscopic procedures such as a colonoscopy. A colonoscopy is the passage of a long, flexible tube through the colon, which allows doctors to see what is happening inside it.

Call Healthline 0800 611 116 if you are unsure what you should do.

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