Crohn's disease

When to get urgent help

Call 999 or go to A&E if:

• tummy pain came on very suddenly or is severe, or it hurts when you touch your tummy (NHS)
• you cannot poo or fart (NHS)
• you are vomiting blood, or your vomit looks like ground coffee (NHS; Crohn's & Colitis UK)
• you are bleeding non-stop from your bottom, or there is a lot of blood — for example, the toilet water turns red or you see large blood clots (NHS)
• your poo is bloody or black, sticky and extremely smelly, with tummy pain (NHS)
• you have severe tummy pain with a high temperature and a fast heartbeat, or signs of severe dehydration (Crohn's & Colitis UK)
• you have a stoma and think it may be blocked — for example, no wind or poo, a swollen tummy, or being sick (Crohn's & Colitis UK)
• someone has collapsed (NHS)

Do not drive yourself to A&E. Ask someone to drive you, or call 999 for an ambulance. Bring any medicines you take with you.

Ask for an urgent GP appointment, get help from NHS 111, or use your IBD advice line if:

• your poo is black or dark red, or you have bloody diarrhoea (NHS)
• tummy pain gets much worse or keeps coming back, diarrhoea does not go away after a few days, or you are losing weight without trying (NHS)
• a flare is not settling with your agreed plan — contact your IBD team or GP, and call NHS 111 if you cannot reach them (Crohn's & Colitis UK)
• you have a painful swelling near your bottom with a high temperature (Crohn's & Colitis UK; NHS)
• you have side effects from your medicine that worry you — contact your IBD team or GP as soon as possible (Crohn's & Colitis UK)

Hospital IBD advice lines and the Crohn's & Colitis UK helpline (0300 222 5700) are not emergency services (Crohn's & Colitis UK helpline; IBD Services Map). See a GP if you think you could have Crohn's, or if you have Crohn's and your symptoms are getting worse or treatment is not helping (NHS).

If you have thoughts of suicide or self-harm, call NHS 111 or go to your nearest A&E. You can also call Samaritans on 116 123, any time of day (Crohn's & Colitis UK).

What is Crohn's disease?

Crohn's disease is a long-term condition where part of the gut becomes inflamed. It cannot currently be cured, but treatment can help people stay without symptoms for long periods (in remission) (NHS). It is one of the main types of inflammatory bowel disease (IBD).

Crohn's can affect any part of the gut, from the mouth to the bottom, but is most common in the small bowel and colon. Inflammation is often patchy, with healthy sections in between, and can go through all the layers of the bowel wall — which is why abscesses and fistulas can develop (Crohn's & Colitis UK). Ulcerative colitis, the other main type of IBD, causes ulcers and inflammation in the rectum and large bowel (colon) (NHS).

Symptoms

Symptoms depend on which part of the gut is affected and can include (NHS; Crohn's & Colitis UK):

• diarrhoea
• blood or mucus in your poo
• tummy pain
• tiredness
• losing weight and loss of appetite
• pain around your bottom
• in children, growing poorly or delayed puberty

Symptoms usually come and go: times when they are active are called flare-ups, and times when they settle are called remission. A flare-up can last from a few days to several months. Crohn's can also cause problems outside the gut, such as joint pain, sore eyes and skin rashes (NHS).

How it is diagnosed

There is no single test for Crohn's (NHS).

• GP tests — blood tests and tests on a poo sample (NHS). A poo test called faecal calprotectin can help tell inflammatory bowel disease apart from irritable bowel syndrome in adults with recent lower-gut symptoms, when cancer is not suspected (NICE HTG320; ACG 2025).
• Hospital tests — a colonoscopy or other camera test, small tissue samples (biopsies), and scans such as MRI, CT or ultrasound (NHS). UK guidance suggests MRI as the first scan for looking at the small bowel (BSG 2025).
• Monitoring — faecal calprotectin is also used to keep track of Crohn's. When symptoms are settled, a normal calprotectin with a normal CRP blood test makes active inflammation unlikely (AGA 2023; BSG 2025).

Complications

• Strictures — a narrowed section of gut that can cause cramping pain, bloating, sickness or a blockage (NHS; Crohn's & Colitis UK).
• Fistulas and perianal disease — a fistula is a tunnel from the bowel to another part of the body, such as the skin, bladder or vagina. Fistulas around the bottom are the most common type, and abscesses can also develop (NHS; Crohn's & Colitis UK). See also anal fistula.
• Anaemia and nutrition — iron-deficiency anaemia is common; low vitamin B12 can follow inflammation or surgery at the end of the small bowel; vitamin D can be low; and bones can become thinner, especially with steroid use. Your IBD team checks and treats these (Crohn's & Colitis UK; NICE NG129).
• Bowel cancer — Crohn's affecting the colon increases bowel cancer risk, and people at higher risk are offered regular colonoscopies (NHS; Crohn's & Colitis UK). The British Society of Gastroenterology suggests a risk-assessment colonoscopy about 8 years after symptoms began (BSG 2025); NICE CG118 uses 10 years for Crohn's colitis affecting more than one segment of the colon (NICE CG118). Crohn's limited to the small bowel does not need this extra surveillance (BSG 2025).

Pregnancy and fertility

Fertility is usually similar to people without Crohn's when it is well controlled, but active Crohn's can make it harder to get pregnant and raise the risk of problems in pregnancy (NHS; Crohn's & Colitis UK). Talk to your IBD team before trying for a baby: European guidance recommends aiming for remission before conception, and some medicines, such as methotrexate, must not be used in pregnancy (ECCO 2023). Some medicines can also affect male fertility (NHS).