Does bowel cancer cause change in bowel habits?

A bowel tumour can narrow the passage or affect how stool moves, causing new constipation, diarrhoea, alternating patterns, narrower stools, urgency, or a feeling that the bowel has not emptied. These changes can also come from infection, medicines, diet, irritable bowel syndrome, or other non-cancer causes. The pattern, how long it lasts, and accompanying symptoms help a clinician decide what examination or test is appropriate.

Record when the change began, how often you open your bowels, stool appearance, pain, bleeding, and any medicines or diet changes. Arrange a medical assessment for a new or ongoing pattern, especially when it is different from your usual bowel function. A clinician may ask about family history and may recommend examination, blood tests, stool testing, or bowel investigation.

Seek urgent help for severe or worsening abdominal pain, repeated vomiting, marked swelling, inability to pass stool or gas, or heavy rectal bleeding. Contact a clinician promptly for blood mixed with stool, black stools, dizziness, or bowel changes accompanied by persistent fatigue or unintended weight loss.

Ask what could explain the pattern, whether you need testing for anaemia or hidden blood, and which bowel investigation fits your symptoms. Ask how to prepare, when results will be available, and which changes should prompt earlier contact.