Seeing blood when you open your bowels is worrying. Most often it comes from piles or a small tear (fissure), but bleeding should not be assumed to be piles without checking, because polyps and bowel cancer can bleed in the same way.
What the bleeding looks like
- Bright red blood on the tissue or dripping into the bowl: usually from near the anus, such as piles or a fissure
- Blood mixed into the stool, or darker red: may come from higher up in the bowel, such as polyps, inflammation (colitis) or cancer
- Black, sticky, tar-like stool: may be bleeding from the stomach or duodenum, such as an ulcer. This needs prompt medical attention.
- No visible blood, but a positive stool test (FIT): needs a colonoscopy
Things that change stool colour but are not blood
Red dragon fruit and beetroot can turn stool red. Iron tablets and some stomach medicines can turn it black or dark green. If you are not sure, see a doctor.
When a colonoscopy is advised
- Blood mixed with the stool, or bleeding that keeps coming back
- A change in bowel habit, weight loss, anaemia or abdominal pain
- A family history of colorectal cancer or polyps
- Age 45 or above, when colorectal screening is due anyway (see colorectal cancer screening)
A colonoscopy looks at the whole bowel, finds the source, and allows polyps to be removed during the same procedure. If piles are the cause, they can then be treated, for example with rubber band ligation or HET.
Seek urgent care at an emergency department for heavy bleeding, passing clots, black stools with dizziness or fainting, or bleeding with severe abdominal pain.
General information only. Reviewed by Dr Chia Chung King, 2026-11-13. Book a consultation.