What Are the Symptoms of Bowel Cancer?

Bowel cancer can present with blood in the stool, a lasting change in bowel habits, abdominal pain, tiredness or unexplained weight loss. Some people have no noticeable symptoms at first, which is why an assessment or screening discussion can matter even when you feel well. These symptoms also have many causes that are not cancer, including haemorrhoids, infections, dietary changes and other bowel conditions. A clinician can help work out what is causing them.

Bleeding may appear as bright red blood, darker blood mixed through the stool, or black, tar-like stool. A change in bowel habits can include new constipation, looser stools, more frequent bowel movements, narrower stools, or a feeling that the bowel has not emptied. Cramping or persistent abdominal discomfort may occur, sometimes with bloating.

Ongoing bleeding can contribute to tiredness or breathlessness through iron deficiency, even when the amount of blood is not obvious. Unexplained weight loss, reduced appetite or a new loss of energy can also accompany bowel cancer. The pattern, persistence and combination of symptoms are more useful to a clinician than any single symptom by itself.

Arrange a medical appointment if a bowel change, bleeding, pain, fatigue or weight loss does not settle, keeps returning, or is unusual for you. Record when it began, how often it happens, what the stool looks like, and whether you have pain, fever, vomiting or reduced appetite. Tell the clinician about medicines such as blood thinners, family history of bowel cancer or polyps, and any known Lynch syndrome or familial adenomatous polyposis.

An assessment may include questions about your symptoms, an examination, blood tests and stool testing. Depending on the findings, a clinician may arrange further bowel examination or imaging. Do not delay an appointment because bleeding is painless or intermittent.

Seek urgent medical help for heavy or continuing rectal bleeding, black stools with weakness or dizziness, severe or worsening abdominal pain, repeated vomiting, marked swelling of the abdomen, or inability to pass stool or gas. These signs can indicate significant bleeding or a bowel blockage and need prompt assessment. If you feel faint, confused or unusually weak, ask someone to help you reach emergency care.

You could ask: What might explain my symptoms? Do I need blood or stool tests? Should I have a bowel examination or imaging? Could my medicines or family history affect the assessment? What changes should prompt urgent help, and when should I follow up if symptoms continue?