Understanding Crohn's.
Plain-language, evidence-based information about intestinal Crohn's disease — what it is, how it's diagnosed, how it's treated, and how to live well with it.
The Basics
Crohn's disease is a chronic form of inflammatory bowel disease (IBD) that can affect any part of the digestive tract, most often the small intestine and colon.
What it is
Crohn's is a lifelong condition where the immune system drives inflammation in the gut wall. It tends to run a relapsing–remitting course, with flares and periods of calm.
Where it strikes
It most commonly involves the end of the small intestine (terminal ileum) and the beginning of the colon, but it can appear anywhere from mouth to anus — often in patchy "skip" areas.
Why it happens
The exact cause is unknown. It reflects a mix of genetics, the gut microbiome, immune response, and environmental triggers such as smoking. It is not caused by anything you did.
How it behaves
Over time, ongoing inflammation can lead to narrowing (strictures), tunnels between organs (fistulas), or abscesses. Early, consistent treatment helps prevent these complications.
Common Symptoms
Symptoms vary widely depending on where the disease is active and how severe it is.
- Persistent diarrhea, sometimes with urgency
- Crampy abdominal pain, often in the lower-right belly
- Fatigue and low energy
- Unintended weight loss and reduced appetite
- Fever during flares
- Blood in the stool (more typical of colonic involvement)
- Symptoms outside the gut — joint aches, skin or eye inflammation
How It's Diagnosed
There is no single test for Crohn's. Diagnosis pieces together your story, exam, labs, scopes, and imaging.
Colonoscopy & biopsy
The cornerstone — a camera examines the colon and terminal ileum, and small tissue samples confirm the pattern of inflammation.
Imaging
MR enterography or CT enterography map the small bowel for inflammation, strictures, and fistulas that scopes can't reach.
Lab work
Blood and stool tests (including CRP and fecal calprotectin) gauge inflammation and help track response to treatment.
Capsule endoscopy
In selected cases, a swallowed camera surveys the small intestine when other tests are inconclusive.
Treatment
The goals are to calm inflammation, heal the gut lining, keep you in remission, and avoid complications. Care is tailored to disease location, severity, and your priorities.
Medical therapy
- Steroids — short courses to settle acute flares (not for long-term control)
- Immunomodulators — thiopurines or methotrexate to maintain remission
- Biologics — anti-TNF, anti-integrin, and anti-IL-12/23 antibodies that target specific immune pathways
- Small-molecule drugs — newer oral options such as JAK inhibitors for selected patients
- Nutrition therapy — exclusive enteral nutrition is especially useful in children and some adults
When surgery is part of the plan
Many people with Crohn's eventually benefit from surgery — not as a failure, but as a tool to remove badly damaged segments, relieve blockages, or treat complications. Surgery is not a cure, so medical therapy usually continues afterward to protect the remaining bowel.
- Resection — removing a diseased segment (commonly the terminal ileum) and rejoining healthy bowel
- Strictureplasty — widening a narrowed segment while preserving bowel length
- Treating complications — addressing abscesses, fistulas, or obstructions
Have perianal Crohn's?
Crohn's that affects the area around the anus — fistulas, abscesses, and fissures — is a distinct topic with its own specialized care. For dedicated, plain-language information on perianal Crohn's disease, visit our companion site pcrohns.org.
Common Questions
Quick, plain-language answers to the questions we hear most.
Is Crohn's disease curable?
There is no cure yet, but modern treatment can control the disease so well that many people reach lasting remission and live full, active lives. The aim is durable control and healing of the gut lining.
Is Crohn's the same as ulcerative colitis?
Both are forms of IBD, but they differ. Crohn's can affect any part of the digestive tract in patchy areas and through the full thickness of the wall; ulcerative colitis is limited to the colon and its inner lining. Sometimes the distinction is unclear early on — see ibdunclassified.org.
Does diet cause or cure Crohn's?
Diet does not cause Crohn's, and no single diet cures it. Nutrition matters a great deal, though — some diets help manage symptoms, and dedicated nutrition therapy can treat active disease in certain situations. A dietitian experienced in IBD is invaluable.
Will I need surgery?
Not everyone does, but many people with Crohn's have surgery at some point. When it's needed, it's a planned tool to remove damaged bowel or fix complications — not a sign of failure. Medication usually continues afterward to protect the rest of the bowel.
Does smoking affect Crohn's?
Yes — smoking clearly worsens Crohn's disease, increasing flares, complications, and the need for surgery. Quitting smoking is one of the most powerful things you can do for your gut.
Can I live a normal life with Crohn's?
Most people with well-managed Crohn's work, travel, exercise, and raise families. Staying on your treatment plan, keeping up with monitoring, and partnering with your care team are the keys to a full life.
Living Well
Day-to-day habits and preventive care that help you stay in remission and feel your best.
Stay on treatment
Crohn's can be quiet even while inflammation continues. Keeping up with medication and monitoring — even when you feel fine — prevents flares and complications.
Don't smoke
Quitting smoking measurably improves the course of Crohn's. It's the single most impactful lifestyle change.
Mind your nutrition
Work with an IBD dietitian to maintain weight, correct deficiencies (iron, B12, vitamin D), and find what your gut tolerates.
Keep up preventive care
Vaccinations, bone-health checks, and cancer surveillance matter — especially with long-standing disease or immune-suppressing therapy.
Tend your mental health
Living with a chronic illness is hard. Stress management and support — professional or peer — are part of good IBD care, not extras.
Know your flare signs
Learn your personal early warning signs and have a plan with your team for what to do when a flare starts.
The IBD Family of Sites
crohnz.org is part of a family of plain-language IBD education sites from the Holubar Lab.
About
crohnz.org is an educational project from the Holubar Lab, led by Stefan D. Holubar, MD, MS, Professor of Surgery in the Department of Colon & Rectal Surgery at Cleveland Clinic. Our aim is to translate the best available evidence on Crohn's disease into clear language that patients, families, and clinicians can use.