Why does Crohn's disease cause blood in stool?

Crohn's disease can cause sores and fragile areas in the digestive tract. When inflamed tissue is rubbed by passing stool, it may bleed. Blood may be bright red, mixed with stool, or make stool appear darker depending on where it comes from. Blood in Stool is a common presentation of Crohn's Disease, especially when disease activity affects the bowel.

Bleeding is not a reliable measure of how serious a flare is on its own. Small amounts can still need review, and blood can also come from causes unrelated to Crohn's disease, such as haemorrhoids, infection or a tear near the anus.

Contact the clinician or inflammatory bowel disease team who manages your treatment and describe the amount, colour and frequency of bleeding, along with pain, diarrhoea and dizziness. Keep taking prescribed treatment unless they tell you otherwise. Drink fluids regularly, particularly if loose stools are also present.

Avoid starting medicines that can increase bleeding or irritate the gut without professional advice. If you use a toilet bowl cleaner, do not try to judge blood colour through coloured water; note what you see on the tissue or stool instead.

Seek urgent medical care for heavy bleeding, black tar-like stool, clots, fainting, severe weakness, a racing heartbeat, severe abdominal pain, fever, or repeated vomiting. Contact your care team promptly for any new or increasing rectal bleeding, even when you otherwise feel well. Rapid assessment helps identify ongoing inflammation and other possible causes.

Could this bleeding be from active Crohn's disease or another source? Do I need blood tests, stool tests or an examination? What change in colour or amount should prompt urgent care?