What should you know about change in bowel habits and weight loss?

Possible explanations include infection, inflammation, altered thyroid function, medicine effects, problems absorbing food and bowel disease. Bowel or rectal cancer can also present with a sustained bowel change and weight loss, but the symptom combination does not establish cancer.

A change may involve new constipation or diarrhoea, alternating between them, passing stool more or less often, narrower stool, urgency, incomplete emptying, mucus or blood. Unplanned weight loss means losing weight without intending to through changes in eating or activity. The pattern, persistence and associated symptoms help guide the assessment.

A clinician may ask about abdominal pain, appetite, fatigue, bleeding, family history, travel, diet and medicines. Examination can include the abdomen and rectum. Depending on the findings, blood or stool tests, imaging, or a camera examination of the bowel may be recommended.

Book a clinical appointment rather than repeatedly treating the change yourself. Record when it began, stool frequency and appearance, any visible blood, abdominal symptoms, appetite and weight trend. Bring a list of medicines and supplements, including laxatives, antidiarrhoeal products and iron tablets.

Keep drinking fluids unless a clinician has restricted them, but avoid starting a restrictive diet that could worsen weight loss before the cause is understood. If testing is arranged, ask how to prepare and whether any medicine needs adjustment. Do not stop prescribed treatment without instructions.

Seek urgent help for heavy rectal bleeding, black tar-like stool, fainting, severe or steadily worsening abdominal pain, a swollen abdomen with repeated vomiting, or inability to pass stool or wind. These features can signal significant bleeding or bowel obstruction.

Arrange prompt review if the bowel change persists, weight continues to fall, blood recurs, fatigue becomes marked, or symptoms wake you from sleep. Escalation is based on these warning features and their progression, not on an assumption about the diagnosis.

Useful questions include: Which causes fit my pattern? Do I need blood or stool tests? Should my medicines be adjusted? Would bowel imaging or an endoscopic test help? What can I eat while awaiting results? Which new symptoms should send me to urgent care?