How common is blood in stool in ulcerative colitis?

Ulcerative colitis inflames the lining of the large bowel. Inflamed lining can become fragile and bleed during bowel movements. Blood may appear with loose stool, mucus, urgency, cramping, or a need to pass stool more often. Symptoms can change over time. A flare is possible, but blood alone cannot confirm that inflammation is the cause or show how active it is.

Contact the clinician managing your ulcerative colitis when bleeding is new, more frequent, or different from your usual symptoms. Keep track of bowel movements, visible blood, abdominal pain, temperature, and medicines you have taken. Continue prescribed treatment unless a clinician tells you otherwise. They may arrange stool or blood tests, review treatment, or assess for another cause of bleeding.

Seek urgent care for heavy bleeding, faintness, fast worsening abdominal pain, a swollen abdomen, fever with feeling very unwell, black tar-like stool, or inability to keep fluids down. Contact a clinician promptly if diarrhoea and bleeding are escalating or you feel weak and dehydrated. These signs require timely assessment even if you have had similar flares before.

Ask whether the bleeding could represent active inflammation, whether infection or a medicine effect needs checking, and what your personal flare plan advises. Discuss which symptoms should lead you to contact the clinic outside routine appointments.