Crohn's disease: symptoms, causes, tests and treatment

In short

• Crohn's disease is a chronic inflammatory bowel disease (IBD). Abnormal immune reactions inflame the digestive tract, most often the small intestine and the beginning of the large intestine.
• The most common signs are diarrhea, belly cramping and pain, and weight loss. Fatigue, fever, poor appetite, joint pain and anemia are other possible signs.
• The exact cause is unknown. Genes, the immune system, the gut microbiome and the environment all seem to play a part, and smoking may double the chance of developing it.
• No single test confirms it. Diagnosis combines blood and stool tests, endoscopy with biopsies and imaging.
• It cannot be cured at present, but medicines and sometimes surgery can control inflammation. Do not stop or change prescribed treatment without talking to your doctor.

What Crohn's disease is and who gets it

Crohn's disease is one type of inflammatory bowel disease (IBD). The inflammation can develop anywhere from the mouth to the anus, though it most often affects the small intestine and the first part of the large intestine. Some people also have inflammation in the joints, skin, eyes, liver and bile ducts, kidneys or lungs.

NIDDK estimates that 1 million people in the United States have Crohn's disease, and says its frequency has been rising in the U.S. and elsewhere for reasons that are not known. It can begin at any age but is more likely between ages 20 and 29.

Symptoms

• Diarrhea, sometimes with blood or mucus in the stool.
• Belly cramping and pain.
• Weight loss, loss of appetite, nausea or vomiting.
• Tiredness and feeling generally unwell, fever, and anemia.
• Pain around the anus.
• Red or painful eyes, sore joints, and red, tender bumps under the skin.
• In children, poor growth or delayed puberty.

Symptoms depend on where the inflammation is and how severe it is. They tend to come and go: periods of flare-ups alternate with periods of remission, when you feel well. Infections can cause similar symptoms, which is one reason the diagnosis needs tests.

Causes and risk factors

Researchers believe an abnormal immune reaction against bacteria that normally live in the intestines is involved. People with IBD also show differences in their gut microbiome compared with people without it. Stress and certain foods do not cause the disease, though they can make symptoms worse.

• Smoking. Research has shown that it may double the chance of developing Crohn's disease.
• Family history, such as a parent or sibling with the disease.
• Genes.
• Some medicines, including antibiotics, birth control pills and NSAIDs, may slightly raise the risk.
• A recent stomach bug or an appendix removed in recent years are also listed by the NHS.

Everyday steps while you wait for care

1. Book the visit.If you think you may have Crohn's disease, make an appointment with your primary care provider. Bring a list of symptoms, how long they last, and any family history of bowel disease.
2. Keep a food and symptom diary.Doctors sometimes suggest one to spot foods that seem to make symptoms worse. It does not replace tests.
3. Do not smoke.Stopping smoking is advised, because smoking is a known risk factor.
4. Be careful with painkillers.NSAIDs such as ibuprofen can worsen symptoms. Ask your doctor before using any over-the-counter medicine, supplement or alternative treatment.
5. Eat as well as you can.Symptoms can reduce appetite and inflammation can limit nutrient absorption, so ask your doctor about an eating plan instead of cutting out food groups on your own.

When to see a doctor

• Diarrhea, belly pain or weight loss that lasts or keeps returning.
• Blood or mucus in your stool.
• You have Crohn's disease and your symptoms get worse or your treatment does not seem to be helping.
• Your child is not growing well or puberty is late.

Contact a doctor urgently for black or dark red stools or bloody diarrhea. Red flags, call 911 now: severe belly pain with repeated vomiting, a swollen belly that is hard to the touch, heavy rectal bleeding, fainting or sudden confusion. Crohn's disease can cause a blocked intestine, abscesses and life-threatening bleeding.

How doctors diagnose it

Your provider asks about symptoms and family history, examines you, and usually orders a combination of tests. According to the NHS, no single test confirms Crohn's disease, so diagnosis can take time.

• Blood tests, which can show anemia, a high white blood cell count and raised C-reactive protein, a marker of inflammation.
• Stool tests to look for inflammation and to rule out certain infections.
• Endoscopy, the most accurate method: colonoscopy, enteroscopy or upper GI endoscopy, with biopsies if needed.
• Capsule endoscopy, in which you swallow a small camera that records the small intestine.
• Imaging such as CT, MRI or an upper GI series with barium.

Your own results are for your doctor to interpret. A single abnormal number does not prove the disease.

Treatment in general terms

Treatment aims to reduce inflammation, relieve symptoms and keep the disease in remission. Medicines can bring on and maintain remission without removing the disease. The main classes are corticosteroids, used only short term, immunosuppressants, biologics, and for some adults who do not respond to other medicines, small molecule medicines. Others treat symptoms or complications: for example antibiotics for abscesses and fistulas, or medicine for severe diarrhea. All are used only as prescribed by a doctor.

In the hospital, bowel rest can be used for complications, with nutrients given by mouth, a feeding tube or an IV. NIDDK says 30% to 55% of people need surgery within 10 years of diagnosis, to treat complications such as fistulas, abscesses, blockages, bleeding, or inflammation that does not respond to medicines. Surgery does not remove the disease itself, and the NHS notes that symptoms can return elsewhere in the gut afterward.

Food and Crohn's disease

Foods do not cause Crohn's disease, but some may make symptoms worse in some people. Your doctor may recommend changes based on your symptoms and medicines. These can include smaller, more frequent meals and avoiding carbonated drinks, popcorn, nuts or high-fiber foods. If your body is not absorbing enough nutrients, supplements may be suggested. Check with your doctor before starting any.

Questions and answers

Sources

1. NIDDK — Definition & Facts for Crohn's Disease
2. NIDDK — Symptoms & Causes of Crohn's Disease
3. NIDDK — Diagnosis of Crohn's Disease
4. NIDDK — Treatment for Crohn's Disease
5. NHS — Crohn's disease
6. MedlinePlus — Crohn's Disease

Sources checked on 28 October 2026.