How common is diarrhoea in ulcerative colitis?

Ulcerative colitis causes inflammation in the lining of the large bowel. That inflammation can reduce the bowel's ability to absorb water and create a strong need to pass stool. Symptoms can change over time, including periods when they are quieter and periods when they are more active. Diarrhoea can also result from infections, food changes, or medicines, so a change deserves context.

Keep taking prescribed ulcerative colitis treatment unless your clinician tells you otherwise. Note the pattern of stools, urgency, blood, pain, fever, and any possible trigger, as this can help your care team assess a flare or another cause. Drink regularly and use a simple diet that you can tolerate if symptoms are making eating difficult.

Contact your inflammatory bowel disease team or clinician promptly for increasing diarrhoea, new blood in stool, fever, worsening pain, or symptoms that disrupt your usual activities. Seek urgent care for severe abdominal pain, a swollen abdomen, fainting, confusion, heavy rectal bleeding, or signs of dehydration. These symptoms need assessment because they can signal a complication or substantial fluid loss.

Ask whether the change could represent active inflammation, an infection, or a medicine effect; ask which symptoms you should record and when your current treatment plan needs review.