Complications of Crohn's disease
BMJ Group Medical Reference
Common symptoms of Crohn's are diarrhoea and stomach pain, but it's also possible to get more serious problems.
If you get severe symptoms of Crohn's disease, you'll probably need to go to hospital.  Some complications end up needing treatment with surgery.
You should talk to your doctor whenever your symptoms get worse. Particular warning signs are a temperature, severe pain, blood in your stools, bloating, or feeling dizzy or dehydrated. See your doctor straight away if any of these happen. It's also important to get help quickly if you can't go to the toilet, can't stop being sick, or get pus leaking from your bottom or from anywhere on your skin.
Here are some of the complications that can happen with Crohn's disease.  They may sounds alarming. But remember that not everyone gets these complications.
An infection. Crohn's can sometimes damage your bowel and lead to an infection or an abscess (a pocket of pus inside your body). If this happens, you might get a temperature or have a tender spot on your abdomen. Your doctor might recommend antibiotics to treat the infection.
A blockage. If Crohn's causes a narrow section in your bowel, it can get blocked. A blocked bowel can cause pain, will make you bloated and constipated, and you may vomit. It needs urgent treatment. You might be given steroids to reduce inflammation and widen the blocked section of bowel. Or doctors might put a tube into your nose, down your throat and into your bowel to suck out anything causing the blockage. If these things don't work, you may need surgery.
A hole in your bowel. This is called a perforation. It can be very painful. It needs emergency treatment, because the contents of your bowel can leak out, causing a dangerous infection. You'll feel generally ill and get a temperature. You'll need surgery to repair the hole and antibiotics (given as a drip) for the infection.
Scar tissue. Over time, damage to your bowel can cause scar tissue to build up. This creates a narrow section of bowel called a stricture. A narrow section of bowel can keep getting blocked. If this happens, your doctor might advise you to eat less fibre (found in foods like nuts, dried fruit and beans). If eating less fibre doesn't help, you might need surgery to remove a stricture.
Damage to the skin around the anus. You could get a tear in the skin (an anal fissure) or a problem where the anus tightens and makes it difficult to pass stools (this is called anal canal stenosis). If you get one of these problems, your doctor might suggest antibiotics to prevent infections in the damaged skin and help it to heal. Anal canal stenosis is sometimes treated with surgery.
An abnormal tunnel. A severe complication is when a tunnel forms, creating an abnormal connection between your bowel and another part of your body. This is called a fistula. For example, you can get a hole between your bowel and your bladder, or even between your bowel and your skin. Antibiotics and immunosuppressant drugs can help a fistula to heal, but if drugs don't work, you may need surgery.
An extremely enlarged bowel. This is a rare but serious problem. Warning signs include stomach pain and a bloated abdomen. Your bowel quickly gets wider (becomes dilated). At the same time, bacteria release poisonous chemicals, which build up inside your bowel. The medical term is toxic megacolon. It's extremely dangerous unless it's treated urgently, and there's a good chance of needing surgery.
Arthritis. Crohn's mainly causes inflammation in your bowel, but for some people, it can also affect other parts of their bodies. This probably happens for about 3 in 10 people with more severe Crohn's disease. One problem that can happen is swollen or painful joints (arthritis). Your usual medicine for Crohn's disease might also help with arthritis. Your doctor might also suggest painkillers like aspirin or ibuprofen. Physiotherapy may help too.
Eye problems. Some people with Crohn's disease get red, itchy or swollen eyes. If this happens, you might need to see a specialist eye doctor (an ophthalmologist).
Weak bones. Between 2 in 10 and 5 in 10 people with Crohn's eventually get weaker bones ( osteoporosis). This is more likely to happen as you get older, especially if you haven't been able to stay active. One cause is not getting enough nutrients from food to keep your bones strong. Steroids can also make your bones weaker, so if you've taken steroids for a long time, you're more likely to get this problem. If your doctor prescribes steroids, he or she might suggest regular check-ups to make sure your bones haven't become too weak.