Inflammatory bowel disease: Crohn’s and ulcerative colitis

Crohn’s and ulcerative colitis: the difference

Both are types of IBD, where the immune system causes inflammation in the gut, but they differ in where and how they affect it. Ulcerative colitis affects only the large bowel (the colon and rectum), causing continuous inflammation of the inner lining, often starting at the rectum. Crohn’s disease can affect any part of the digestive tract, from mouth to bottom, though it often involves the end of the small bowel. In Crohn’s, inflammation can occur in patches and go deeper into the bowel wall. These differences affect symptoms and treatment. Sometimes it is hard to tell them apart at first, and the exact diagnosis becomes clearer over time.

Symptoms and flares

IBD tends to follow a pattern of flare-ups, when symptoms are active, and remission, when they settle. Common symptoms include diarrhoea, sometimes with blood or mucus, tummy pain and cramping, an urgent need to go to the toilet, tiredness, and weight loss. Crohn’s can also cause mouth ulcers and problems around the bottom. Because the inflammation affects the whole body, some people get joint pains, eye problems, skin rashes or anaemia. Symptoms range from mild to severe. A severe flare, with frequent bloody diarrhoea, fever, a racing heart or severe tummy pain, needs urgent medical attention, as it can occasionally become dangerous.

How it is diagnosed

Diagnosing IBD involves several steps to confirm inflammation and rule out other causes. Blood tests check for inflammation and anaemia, and a stool test called faecal calprotectin can show inflammation in the gut, helping tell IBD from IBS. The key test is usually a colonoscopy, where a camera examines the bowel lining and small samples (biopsies) are taken to look at under a microscope. Further scans, such as MRI, may be used, especially in Crohn’s, to see parts of the small bowel a camera cannot reach. Reaching a clear diagnosis, and working out how much of the gut is affected, guides the choice of treatment.

Treatment on the NHS

Treatment has two aims: to calm a flare and bring the disease into remission, then to keep it there. Several types of medicine are used. Anti-inflammatory medicines called aminosalicylates are often used in ulcerative colitis. Steroids can settle a flare but are not for long-term use. Medicines that damp down the immune system, including newer biologic treatments given by injection or drip, help many people stay in remission. The choice depends on the type, severity and site of disease. Some people with Crohn’s or ulcerative colitis need surgery, for example to remove a badly affected part of the bowel. A specialist IBD team, including nurses and dietitians, guides care.

Living well with IBD

Living with IBD means learning what helps you and staying in touch with your team. Take medicines as prescribed, even when you feel well, as stopping can trigger a flare. Attend regular reviews and blood tests. Some people find certain foods worsen symptoms during a flare, and a dietitian can give tailored advice; there is no single diet that suits everyone. Stopping smoking is especially important in Crohn’s, as it makes the disease worse. Because IBD raises the long-term risk of bowel changes, you may be offered regular monitoring. Support groups can help with the emotional side. Contact your team promptly if you have a flare or new symptoms.