Why does bowel cancer cause change in bowel habits?

A growth can narrow the passage or disturb the coordinated movement of the bowel. This may make stool harder to pass, cause looser stools, or create a pattern that differs from your usual routine.

When the bowel channel becomes narrower, stool may take longer to pass and may be thinner than usual. Irritation of the bowel lining can also trigger urgency, cramping, or looser bowel movements. Some people notice constipation and diarrhoea occurring at different times rather than one consistent change.

These changes can have many causes, including infection, medicines, food intolerance, or other bowel conditions. A change that continues, keeps returning, or occurs with blood in the stool deserves assessment. The symptom alone cannot identify its cause.

Write down when the change began, how often you open your bowels, whether the stool is narrower or looser, and whether you notice mucus, blood, pain, or urgency. Take the list to a clinician. They may ask about medicines, family history, diet, and other symptoms before deciding whether tests are needed.

Keep drinking fluids unless a clinician has advised a restriction, and avoid taking repeated laxatives or anti-diarrhoeal medicines without advice when the change is unexplained.

Arrange medical care promptly for a persistent or recurrent bowel change, especially with rectal bleeding, dark stools, ongoing abdominal discomfort, tiredness, or unplanned weight loss. Seek urgent help for severe abdominal pain, repeated vomiting, marked swelling, or inability to pass stool or gas.

Could my bowel change be related to a blockage, irritation, bleeding, or another condition? Which examination or stool and bowel tests might clarify the cause? What changes should make me contact you sooner?