Crohn's Disease

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Condition Basics

What is Crohn's disease?

Crohn's disease is a lifelong inflammatory bowel disease (IBD). In Crohn's disease, parts of the digestive system get swollen and have deep sores called ulcers. This can result in symptoms such as belly pain and diarrhea.

Crohn's disease in part of the digestive tract.

Crohn's disease can affect any part of the digestive tract (which goes from the mouth to the anus). Most common is Crohn's disease that affects the ileum (the part of the small intestine that joins the large intestine). But Crohn's disease can be in multiple places in the digestive tract at the same time.

What causes it?

Doctors don't know what causes Crohn's disease. You may get it because your immune system has an abnormal response to normal bacteria in your intestine. Other kinds of bacteria and viruses may also play a role in causing the disease. Crohn's disease may run in families. Smoking puts you at a higher risk.

What are the symptoms?

The main symptoms of Crohn's disease are belly pain and diarrhea (sometimes with blood). Losing weight without trying is another common sign. You may have only mild symptoms or go for periods of time without symptoms. A few people have ongoing, severe symptoms.

How is it diagnosed?

Your doctor will ask you about your symptoms and do a physical exam. You may also have X-rays and lab tests to find out if you have Crohn's disease. You may have tests that look inside the colon, and you may have a biopsy.

How is Crohn's disease treated?

Your treatment will depend on your symptoms and how bad they are. The main treatment for Crohn's disease is medicine. Mild symptoms may be treated with over-the-counter medicines to stop diarrhea. You may also use prescription medicines to treat and prevent symptoms. Some people need other treatments, such as surgery.


The main symptoms of Crohn's disease are belly pain and diarrhea (sometimes with blood). Losing weight without trying is another common sign.

Less common symptoms include mouth sores, bowel blockages, anal tears (fissures), and openings (fistulas) between organs.

Infections, hormonal changes, smoking, medicines, and lifestyle changes can cause your symptoms to flare up. Your symptoms may be mild, moderate, or severe.

What Happens

Complications of Crohn's disease

Crohn's disease may cause sores, or ulcers, that tunnel through the intestine and into the nearby tissue. These are often around the anus and rectum. These tunnels, called fistulas, are a common problem with Crohn's disease. They may get infected. Crohn's disease can also cause anal fissures. These are narrow tears that extend from the muscles that control the anus (anal sphincters) up into the anal canal.

In long-term Crohn's disease, scar tissue may replace some of the inflamed or ulcerated intestines. This scar tissue can form blockages (bowel obstructions) or narrowed areas (strictures). These can prevent stool from passing through the intestines. Blockages in the intestines also can be caused by inflammation and swelling, which may improve with medicines. Sometimes blockages can only be treated with surgery.

Sometimes symptoms of Crohn's disease develop outside the digestive tract in other parts of the body. This can include in the eyes, liver, blood, and bones.

When to Call

Call 911 anytime you think you may need emergency care. For example, call if:

  • You passed out (lost consciousness).
  • Your stools are maroon or very bloody.

Call a doctor now if you have been diagnosed with Crohn's disease and you have one or more of the following:

  • New or worse belly pain.
  • Fever.
  • Severe dehydration.
  • New or worse nausea or vomiting.
  • New or more blood in your stools.
  • Not passing any stools or gas.
  • Pus draining from the area around the anus, or pain and swelling in the anal area.

If you have any of these symptoms and you have been diagnosed with Crohn's disease, your condition may have become much worse. Some of these symptoms, such as severe belly pain and bloating, also may be signs of toxic megacolon. This is a rare complication of Crohn's disease that requires emergency treatment. Without treatment, it can cause the colon to leak or rupture, which can be fatal.

People who have Crohn's disease usually know their pattern of symptoms. Watch closely for changes in your health, and be sure to contact your doctor if:

  • You have new or worse symptoms, such as your diarrhea gets worse.
  • You are losing weight.
  • You do not get better as expected.

Exams and Tests

Your doctor will ask you about your symptoms and do a physical exam. You may also have lab tests or imaging tests to find out if you have Crohn's disease.

Tests that may be done to diagnose or evaluate Crohn's disease include:

  • Stool analysis. This test looks for blood and signs of infection in a sample of your stool.
  • One or more imaging tests, such as a CT scan or an MRI.
  • Colonoscopy or flexible sigmoidoscopy. In these tests, the doctor uses a thin, lighted tube to look inside the colon.
  • A biopsy. The doctor takes a sample of tissue and tests it to find out if you have Crohn's disease or another disease, such as cancer.
  • Barium X-rays of the small intestine or colon.

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Treatment Overview

Your treatment will depend on the type of symptoms you have and how bad they are. Medicines are the most common treatment for Crohn's disease. Mild symptoms may be treated with over-the-counter medicines to stop diarrhea. Prescription medicines can control or prevent inflammation in the intestines and help relieve symptoms. They also promote the healing of damaged tissues.

People who have more severe, long-lasting symptoms may need other treatments. These may include liquid feedings (supplemental nutrition) to let the intestines rest and heal or surgery to remove the damaged part of the intestine.

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  • Take your medicines exactly as prescribed. Call your doctor if you think you are having a problem with your medicine. You will get more details on the specific medicines your doctor prescribes.
  • Do not take anti-inflammatory medicines, such as aspirin, ibuprofen (Advil, Motrin), or naproxen (Aleve). They may make your symptoms worse. Do not take any other medicines or herbal products without talking to your doctor first.
  • Avoid foods that make your symptoms worse. These might include milk, alcohol, high-fiber foods, or spicy foods. It may help to keep a diary of foods that make symptoms worse.
  • Make sure to get enough iron. Rectal bleeding may make you lose iron. Good sources of iron include beef, lentils, spinach, raisins, and iron-enriched breads and cereals.
  • Drink liquid meal replacements if your doctor recommends them. These are high in calories and contain vitamins and minerals. Severe symptoms may make it hard for your body to absorb vitamins and minerals.
  • Talk to a dietitian to make sure you are getting the nutrition, including vitamins and minerals, that you need.
  • Do not smoke. Smoking makes Crohn's disease worse. If you need help quitting, talk to your doctor about stop-smoking programs and medicines. These can increase your chances of quitting for good.
  • Stay up to date on all immunizations.
  • Follow your doctor's cancer screening recommendations.
  • Seek support from friends and family to help cope with Crohn's disease. The illness can affect all parts of your life. Get counseling if you need it.


Medicines usually are the treatment of choice for Crohn's disease. They can control or prevent inflammation in the intestines. They help to:

  • Relieve symptoms.
  • Promote healing of damaged tissues.
  • Put the disease into remission. And they can keep it from flaring up again.
  • Postpone the need for surgery.

They include:

  • Aminosalicylates. Your doctor may recommend these medicines during a flare-up or at other times.
  • Antibiotics. These treat infections that can occur with Crohn's disease.
  • Biologics. Your doctor may have you try these medicines if other medicines for Crohn's disease haven't worked for you.
  • Corticosteroids. They usually stop symptoms and put the disease in remission. But they aren't used as long-term treatment to keep symptoms from coming back.
  • Immune modulators. You may take these if other medicines don't work, if your symptoms come back when you stop taking steroid medicines, or if your symptoms come back often, even with treatment.


Current as of: October 19, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

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The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.