What Is Crohn’s Disease? Symptoms, Causes, Diagnosis, and Treatment

Crohn’s disease is a chronic type of inflammatory bowel disease, or IBD, that can cause inflammation anywhere in the digestive tract. It often affects the end of the small intestine and the colon. Symptoms can come and go, but ongoing inflammation can lead to complications without appropriate medical care.1

What is Crohn’s disease?

Crohn’s disease is a long-term inflammatory bowel disease. Inflammation can involve the small intestine, large intestine, colon, rectum, or less commonly other parts of the digestive tract. It is often described as transmural inflammation, meaning it can extend through the full thickness of the bowel wall.1

The location of inflammation affects the name doctors may use. Ileitis affects the ileum. Ileocolitis involves the terminal ileum and colon. Crohn’s colitis affects the colon, while jejunoileitis and gastroduodenal Crohn’s disease involve other sections of the small intestine or upper digestive tract. Inflammation may appear in separate patches, sometimes called skip lesions.1

How is Crohn’s disease different from ulcerative colitis?

Crohn’s disease and ulcerative colitis are both forms of IBD, but they affect the bowel differently. The main difference is location: ulcerative colitis is limited to the colon and rectum, while Crohn’s disease can occur anywhere along the digestive tract.1

IBS is different from both conditions. IBS can cause pain, constipation, diarrhea, or bloating, but it does not cause the chronic bowel inflammation seen in IBD.1 Our guide to IBS symptoms explains why symptom overlap should not be used to self-diagnose either condition.

What symptoms can Crohn’s disease cause?

Symptoms vary by the part of the digestive tract involved and whether inflammation is active. Flares can develop gradually or quickly and may include diarrhea, abdominal pain, cramping, reduced appetite, fatigue, fever, weight loss, rectal bleeding, and mouth sores.1

Chronic inflammation or bleeding can contribute to anemia and fatigue. Inflammation in the small intestine can also affect nutrient absorption, including vitamin B12 and vitamin D. Some people develop symptoms outside the gut, such as arthritis, skin inflammation, or eye inflammation.1

Crohn’s disease can also cause perianal disease around the anus. A fistula is an abnormal tunnel between body structures, while an abscess is a pocket of infection. Scar tissue can narrow the bowel into a stricture and, in some cases, lead to intestinal obstruction.1

What causes Crohn’s disease?

There is no single known cause of Crohn’s disease. It appears to involve an abnormal immune response in the gut in people with inherited susceptibility, together with environmental factors and the gut microbiome.1

Food, alcohol, caffeine, and stress do not cause Crohn’s disease. However, individual foods or drinks may worsen symptoms during a flare, and stress can make symptoms feel harder to manage. Smoking is linked with worse Crohn’s disease outcomes, so avoiding tobacco is an important part of care.1

How do doctors diagnose Crohn’s disease?

Crohn’s disease cannot be diagnosed from symptoms alone. Diarrhea, pain, bleeding, fatigue, and weight loss can also occur with infections, IBS, ulcerative colitis, colorectal cancer, celiac disease, and other conditions. A qualified clinician should evaluate persistent or concerning symptoms.1

• A medical history and physical exam help identify symptom patterns, family history, medicines, and red flags.1
• Blood testing may look for anemia, inflammation, dehydration, or nutrition concerns.1
• Stool testing may check for infection and signs of intestinal inflammation.1
• Colonoscopy and biopsy let clinicians view the colon and terminal ileum and examine tissue under a microscope.1
• CT or MRI imaging can help assess small-bowel inflammation, strictures, abscesses, and fistulas.1

For a broader explanation of persistent gut inflammation and the tests that may be used, see our article on intestinal inflammation symptoms, causes, and diagnosis.

What treatments are used for Crohn’s disease?

Treatment aims to lower intestinal inflammation, manage symptoms, prevent flares, and maintain remission. There is no one treatment plan for everyone: the right approach depends on disease location, severity, complications, prior treatment response, infection risk, pregnancy status, and other health factors.1

Medicines for active inflammation and remission

Corticosteroids may be used for short-term control of active inflammation, but they are not intended as long-term maintenance treatment because of important risks with prolonged use. Other options include immunosuppressants, biologics, and small-molecule medicines.1

Human clinical trials support several advanced therapies for appropriate patients. Five-year results from the IM-UNITI trial evaluated ustekinumab maintenance treatment in Crohn’s disease.4 Phase 3 analyses also evaluated upadacitinib for clinical and endoscopic outcomes, including in people with and without prior biologic exposure.3 These medicines can have meaningful risks, including infection-related risks and other treatment-specific side effects, so selection and monitoring belong with an IBD specialist.3 4

Nutrition support, antibiotics, and surgery

Doctors may use antibiotics for selected complications, such as certain infections or perianal disease. In severe illness or hospitalization, bowel rest and enteral nutrition may be part of care under medical supervision.1

Surgery may be needed for a stricture, obstruction, fistula, abscess, severe bleeding, or disease that does not respond to medicine. NIDDK estimates that 30% to 55% of people with Crohn’s disease require surgery within 10 years of diagnosis. Surgery can address complications and improve symptoms, but it does not cure Crohn’s disease.1

For a fuller overview of standard IBD care, read our guide to inflammatory bowel disease treatment.

What lifestyle changes may help people with Crohn’s disease?

Lifestyle support can reduce symptom burden and help protect nutrition, but it does not replace treatment for confirmed active inflammation. The most useful diet plan is often individualized with a gastroenterologist and, when available, an IBD-focused dietitian.1

Some structured nutrition approaches have been studied in selected groups. A randomized trial found that Crohn’s Disease Exclusion Diet plus partial enteral nutrition induced sustained remission in children with mild to moderate Crohn’s disease.2 A 2025 randomized trial studied a whole-food diet in children and young adults with mild to moderate disease, and another pediatric trial evaluated a modified exclusion diet for maintaining remission.7 6 These findings do not mean that one restrictive diet is right for every adult or every type of Crohn’s disease.

• Keep a simple food-and-symptom record to identify personal triggers without unnecessarily restricting nutrition.
• Avoid smoking or seek support to quit.1
• Ask a clinician before using NSAIDs such as ibuprofen or naproxen regularly, as they may aggravate digestive symptoms for some people.1
• Discuss alcohol and caffeine based on your symptoms, medicines, hydration, and nutrition status.
• Use stress-management tools as symptom support, not as a replacement for IBD care.

Which Crohn’s disease option fits which person?

The next step depends on symptoms and test results, not on a single online checklist. New bleeding, weight loss, or persistent diarrhea warrants clinical evaluation rather than self-treatment.1

Does Chia treat Crohn’s disease?

Chia does not currently offer Crohn’s disease diagnosis or IBD-specific prescription treatment in our catalog. Crohn’s disease should be managed with a gastroenterologist because treatment decisions may require endoscopy, imaging, lab monitoring, and care for complications.1

Our current treatments are not substitutes for Crohn’s disease care, and we do not position them as treatment for Crohn’s inflammation, fistulas, strictures, or flares. We can still help readers understand adjacent topics, including Crohn’s disease treatment, IBS-like symptoms, inflammation questions, and metabolic health. If you are considering any treatment while living with IBD, involve your gastroenterology team.

What is the outlook for people with Crohn’s disease?

Crohn’s disease is lifelong, but many people have periods of remission with a treatment plan that fits their disease. Long-term monitoring matters because symptoms do not always match the level of intestinal inflammation, and complications can develop over time.1

Follow-up helps clinicians watch for medication side effects, anemia, nutrition problems, strictures, fistulas, abscesses, and the need to adjust treatment. Staying connected to an IBD team and raising new symptoms early can make care more proactive.1

Keep reading

Digestive Health

Treatment for Crohn's Disease: Medicines, Diet, Flares, and When to Get Care

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Inflammatory Bowel Disease Treatment: Medicines, Diet, Flares, and When to Get Care

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Intestinal Inflammation: Symptoms, Causes, Diagnosis, and When to Get Care