Inflammatory bowel disease (IBD)

Symptoms vary from person to person and can flare up and settle down over time. Common gut‑related symptoms include:

• Ongoing or recurrent diarrhoea, sometimes with mucus or blood
• Cramping or aching abdominal pain, often before opening the bowels
• An urgent need to get to the toilet, with possible incontinence
• Unintentional weight loss and reduced appetite
• Rectal bleeding or blood mixed in with stools

Some people also experience:

• Extreme tiredness, low energy and anaemia
• Joint pains or swelling, mouth ulcers, rashes or eye inflammation
• Perianal symptoms such as pain, discharge, abscesses or fistulas (abnormal tracts) in Crohn’s disease

A few people have very few symptoms and IBD is first suspected because of abnormal blood or stool tests.

Both Crohn’s disease and ulcerative colitis involve inflammation of the gut, but they affect different areas and behave differently.

• Ulcerative colitis only affects the colon (large bowel) and rectum, with continuous inflammation of the inner lining.
• Crohn’s disease can affect any part of the digestive system from the mouth to the anus, often in “patches”, and can involve the full thickness of the bowel wall.

Ulcerative colitis can lead to attacks of acute severe colitis and, if inflammation is not well controlled over many years, can increase the risk of bowel cancer. Crohn’s disease is more likely to cause strictures (narrowing), abscesses and fistulas, and many people with moderate to severe Crohn’s eventually need surgery for these complications.

Inflammatory bowel disease (IBD) is a group of conditions, mainly Crohn’s disease and ulcerative colitis, where there is visible inflammation and damage in the gut that can be detected with tests such as colonoscopy and biopsies.

Irritable bowel syndrome (IBS) is classed as a functional bowel disorder where the bowel looks normal, yet patients experience symptoms similar to IBD but the symptoms are caused by heightened gut sensitivity instead of inflammation. The cardinal symptoms of IBS are ABC: abdominal pain, bloating and changes in bowel habit. IBS does not incur long‑term damage to the gut nor increased cancer risk and may often impact quality of life.

IBD usually needs anti‑inflammatory or immune‑modulating medicines and regular monitoring, whereas IBS is managed with diet, lifestyle measures and symptom‑relief medicines. Some people may have both conditions, so if your IBS symptoms change – for example, you develop weight loss, bleeding or ongoing night‑time diarrhoea – you should be reassessed by a specialist.

IBD is increasingly common in the UK and worldwide. Recent data suggest that around 0.7–0.8% of the UK population live with IBD – more than 500,000 people, or roughly 1 in 123 individuals. It can develop at any age but is most often diagnosed in early adulthood (15–35 years), with a second smaller peak between 50 and 70 years.

IBD is seen in all ethnic groups, but rates are rising particularly quickly in South Asian and Middle Eastern populations and in people who move from low‑ to high‑incidence countries. Having a close family member with IBD may also mean you have a chance of developing IBD, particularly if their disease started at a young age.

The exact cause of IBD is unknown, but it is thought to occur when the immune system overreacts to bacteria living in the gut in someone who is genetically susceptible, influenced by environmental and lifestyle factors. Research suggests that:

• Genetics play a role – more than 200 genes have been associated with IBD, but no single gene causes it.
• The gut microbiome and diet are involved, although specific foods or bacteria have not been proven to “cause” IBD.
• Environmental factors such as smoking, pollution and urban living increase risk, as shown by higher rates in Western countries and in migrants to these regions.

Other autoimmune conditions – such as ankylosing spondylitis, rheumatoid arthritis, psoriasis and primary sclerosing cholangitis – are more common in people with IBD and their families. People with these conditions who experience gut symptoms should consider investigations to exclude IBD.

Inflammatory Bowel Disease risk factors

You may be more likely to develop IBD if:

• A close relative (parent, sibling or child) has IBD.
• You smoke – smoking particularly increases the risk and severity of Crohn’s disease.
• Your diet is high in ultra‑processed foods and sugar and low in fibre, fruit and vegetables.
• You have other autoimmune conditions or a strong family history of autoimmunity.

Many of these factors cannot be changed, but stopping smoking, improving diet and maintaining a healthy weight are positive steps you can take.

The first step is a thorough consultation and examination to understand your symptoms, medical history and family background. Your consultant may recommend:

• Blood tests to check for inflammation, anaemia, vitamin levels and effects on other organs.
• Stool tests, including faecal calprotectin, which helps detect inflammation and specific stool tests to exclude infections.
• Endoscopic tests:
  • Flexible sigmoidoscopy or rigid sigmoidoscopy to look at the lower bowel.
  • Colonoscopy which examines the entire colon and allows biopsies to confirm the diagnosis and assess severity.
  • Small‑bowel imaging such as MRI enterography or CT enterography, and sometimes capsule endoscopy, to assess Crohn’s disease in the small intestine.
  • Gastroscopy if upper‑gut involvement is suspected.

A rigid sigmoidoscopy may be offered during a consultation. For the procedure. you are encouraged to lie on your left side while a thin tube is gently passed into the rectum to view the lower bowel; this usually takes about five minutes and is well tolerated. A colonoscopy is a longer, pre‑booked test with bowel preparation in advance, and you will be fully briefed on how it works and what to expect as part of the consultation.

IBD is a long‑term condition with no simple cure, but modern treatments can control inflammation, reduce symptoms, promote healing of the bowel and lower the risk of complications. At The London Clinic, your treatment plan is tailored to whether you have Crohn’s disease or ulcerative colitis, how active and extensive your disease is, and your personal preferences.

Broad treatment options include:

• 5‑aminosalicylates (5‑ASA) such as mesalazine tablets, enemas or suppositories, especially in mild to moderate ulcerative colitis.
• Corticosteroids such as prednisolone, hydrocortisone or budesonide for short‑term flares, to quickly reduce inflammation; these are not used as long‑term maintenance because of side effects.
• Immunomodulators such as azathioprine, mercaptopurine to maintain remission and reduce the need for steroids in ulcerative colitis.
• Advanced therapy with biologic drugs , including anti‑TNF agents (infliximab, adalimumab, golimumab), anti‑integrins (vedolizumab), cytokine inhibitors (ustekinumab, risankizumab, mirikizumab and guselkumab), usually delivered as infusions or injections
• Advanced therapy with small molecule drugs such as JAK inhibitors (tofacitinib, filgotinib, upadacitinib) and S1P modulators (ozanimod,etrasimod), that are oral preparations
• Dietary interventions, sometimes involving dietitian‑led exclusion diets or specific nutrition plans, particularly in Crohn’s disease.
• Surgery to remove damaged sections of bowel, treat strictures, abscesses or fistulas, or, in some ulcerative colitis cases, remove the colon and create a pouch or stoma.

All treatments are monitored for effectiveness and side effects, using regular blood and stool tests, with colonoscopy surveillance in higher‑risk groups.

What if IBD is not treated?

Without adequate control, ongoing inflammation can lead to complications such as strictures, bowel blockages, perforation, abscesses, severe colitis and the need for emergency surgery. Long‑term uncontrolled colonic inflammation also increases the risk of bowel cancer, which is why regular monitoring and surveillance colonoscopies are important.

Life with Inflammatory Bowel Disease

With modern care, many people with IBD lead full, active lives, working, travelling and raising families. You will usually have periods of remission with no or minimal symptoms, punctuated by flares that are managed with adjustments to treatment. Ongoing support from your consultant, specialist nurses, dietitians and, where needed, psychologists can help you manage fatigue, diet, mental health and the impact on relationships and work.