Inflammatory Bowel Disease (IBD)

What causes IBD

IBD develops when an inappropriate immune response to gut bacteria causes chronic inflammation in genetically susceptible people. Contributing factors include:

• genes: more than 200 gene regions are linked to IBD; having a close relative with IBD raises risk
• gut microbiome changes
• environment: Western diets, urban living, antibiotic exposure in childhood
• smoking: increases risk and severity of Crohn's disease, but is associated with lower UC risk (smoking is still strongly discouraged)
• NSAIDs can trigger flares

IBD is not caused by stress or diet alone, though both can affect symptoms.

Crohn's disease vs ulcerative colitis

See Crohn's disease and ulcerative colitis for more on each.

Symptoms

Bowel symptoms

• persistent diarrhea, sometimes with blood or mucus
• urgency and frequency, including at night
• abdominal pain and cramping
• rectal bleeding
• a feeling of incomplete emptying (tenesmus)
• perianal pain, abscesses or fistulas in Crohn's disease

Whole-body symptoms

• fatigue
• weight loss and reduced appetite
• fever during flares
• anemia
• delayed growth and puberty in children

Outside the gut

• joint pain and arthritis, including spine involvement
• red, painful eyes (uveitis, episcleritis)
• skin conditions: painful red nodules on the shins (erythema nodosum), ulcerating sores (pyoderma gangrenosum)
• mouth ulcers
• primary sclerosing cholangitis, a liver disease mostly linked to UC
• kidney stones and gallstones (Crohn's)
• blood clots

IBD vs IBS

Irritable bowel syndrome (IBS) also causes abdominal pain and altered bowel habits, but there is no inflammation or damage to the gut. IBS does not cause bleeding, weight loss, fever, anemia or abnormal blood tests. A stool calprotectin test helps tell them apart: it is raised in IBD and normal in IBS. Some people with IBD in remission also have IBS-like symptoms.

Diagnosis

• Blood tests: blood count (anemia), CRP, iron, vitamin B12, albumin, liver tests.
• Stool tests: fecal calprotectin for gut inflammation; tests to rule out infection, including C. difficile.
• Colonoscopy with biopsies: the key test to see inflammation, its pattern and extent.
• Imaging of the small bowel: MR or CT enterography, intestinal ultrasound, or capsule endoscopy for Crohn's disease.
• Upper endoscopy if upper GI symptoms are present.

Treatment

The goal is "treat to target": controlling symptoms and healing the bowel lining, which reduces complications and surgery.

Medicines

Treatment is personalized based on disease type, location, severity, risk factors and patient preference. People on immune-suppressing medicines need vaccinations (avoiding live vaccines on some drugs), skin checks and infection screening.

Surgery

• Crohn's disease: removing narrowed or damaged segments, draining abscesses, repairing fistulas. Disease can recur near the join.
• Ulcerative colitis: removing the colon and rectum (proctocolectomy), often with an internal pouch (J-pouch) or a permanent ileostomy, for severe or medication-resistant disease, or dysplasia.

Nutrition and lifestyle

• exclusive enteral nutrition (liquid formula) can induce remission in children with Crohn's
• a dietitian can help with strictures, weight loss and deficiencies (iron, B12, vitamin D)
• stop smoking, especially in Crohn's disease
• avoid NSAIDs where possible
• manage stress and sleep; mental health support helps quality of life

Complications

• strictures and bowel obstruction
• fistulas and abscesses
• toxic megacolon and perforation
• malnutrition and anemia
• osteoporosis
• colorectal cancer, with higher risk after 8 to 10 years of colitis; regular surveillance colonoscopies are recommended

Living with IBD

IBD usually follows a pattern of flares and remission. With modern treatment, most people lead full lives, work, travel and have children. Planning pregnancy while in remission and continuing most IBD medicines during pregnancy gives the best outcomes.

Frequently asked questions

What are the first signs of IBD?

Early signs include diarrhea lasting weeks, abdominal pain and cramping, blood or mucus in the stool, urgency, fatigue and unexplained weight loss. Symptoms often come and go. Persistent bowel symptoms, especially with bleeding or weight loss, should be checked.

What is the difference between IBD and IBS?

IBD causes visible inflammation and damage to the gut, with bleeding, weight loss and abnormal blood or stool tests. IBS causes pain and changes in bowel habits without inflammation or damage. Stool calprotectin and colonoscopy help tell them apart.

Can IBD be cured?

There is no cure for Crohn's disease. Ulcerative colitis can be cured by removing the colon, but most people control it well with medicines. Modern treatments keep many people in long-term remission with healed bowel lining.

What foods should I avoid with IBD?

No single diet works for everyone. During flares, many people find low-fiber, low-fat and lactose-free foods easier. People with strictures should avoid tough, fibrous foods. Keep a food diary and work with a dietitian rather than cutting out whole food groups.

Is IBD hereditary?

Genes play a role: about 10 to 25% of people with IBD have a relative with it, and having a parent or sibling with IBD increases your risk. However, most relatives of people with IBD never develop it.