How common is blood in stool in bowel cancer?

Bowel cancer can bleed into the digestive tract. You may see red blood, darker blood mixed with stool, or a change in the colour of stool. Other possible symptoms include a persistent change in bowel habit, abdominal discomfort, a sensation of incomplete emptying, tiredness, or unintentional weight loss. Haemorrhoids, fissures, infections, and inflammatory conditions can also cause rectal bleeding. The visible colour or amount is not enough to tell these causes apart.

Book a medical assessment for any new, unexplained, or recurrent blood in stool. The clinician may ask about your usual bowel pattern, review medicines, and consider an examination or tests based on your symptoms. Keep a brief record of when bleeding occurs, whether it is mixed with stool, and any change in frequency, pain, fatigue, or appetite. Do not assume that bleeding is harmless because it is painless or because it improves temporarily.

Seek urgent medical care for heavy bleeding, black and sticky stools, fainting, marked weakness, severe abdominal pain, or confusion. Contact a clinician promptly if bleeding continues, bowel habits change persistently, or you are becoming increasingly tired or breathless. These symptoms require assessment, regardless of the underlying cause.

Ask what could be causing the bleeding, which tests may help, and what changes should prompt earlier contact. Share family history of bowel cancer or polyps, previous bowel conditions, recent weight change, and any medicines that can increase bleeding.