What should you know about reasons for change in bowel habits?

Changes can include new constipation, diarrhoea, alternating patterns, narrower stools, urgency or a different frequency. Common triggers include altered diet, low fluid intake, stress, travel, medicines and a stomach or bowel infection. Irritable bowel syndrome and inflammatory bowel disease can also change bowel function.

A change in bowel habits is a common presentation of bowel cancer, while a persistent change can also be a presentation of rectal cancer. Neither symptom confirms either condition; assessment considers duration, examination findings and accompanying signs.

Keep a short record of stool appearance, frequency, pain, food changes, medicines and any blood or mucus. Drink fluids unless a clinician has restricted them, and avoid taking repeated laxatives or anti-diarrhoeal medicines without advice. Arrange a medical review when a new pattern persists, recurs, or interferes with daily life. Your clinician may discuss examination, blood tests or a [Colonoscopy](/treatments/cancer-screening/colonoscopy/) when appropriate.

Seek prompt care for blood in the stool, black stools, unexplained weight loss, ongoing abdominal pain, anaemia symptoms, or a persistent change without an obvious explanation. Seek urgent help for severe or worsening pain, a swollen abdomen with vomiting, inability to pass stool or gas, fainting, or heavy bleeding. These are red flags requiring assessment regardless of whether cancer is suspected.

Ask what pattern you should monitor, whether a medicine or dietary change could explain it, and which tests are suitable. Ask how bowel cancer and rectal cancer are evaluated, and when you should return if the pattern continues.