What Is Crohn's Disease?

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Crohn’s disease is a type of inflammatory bowel disease (IBD). It is an immune-mediated condition that affects many body systems, especially the digestive system. It is a chronic condition that causes inflammation and alternates between periods of active and inactive disease. There is currently no cure, but it is often manageable with medication and lifestyle changes.

Woman sitting on bed holding stomach and lower abdomen

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Symptoms of Crohn’s Disease 

The symptoms of Crohn’s disease mainly affect the digestive system. However, there can also be signs of the disease outside the digestive tract, called extraintestinal manifestations.

Signs and symptoms people with Crohn’s disease may experience include: 

  • Abdominal pain
  • Anemia (a low level of healthy red blood cells)
  • Chronic diarrhea
  • Fatigue
  • Fever
  • Fistula (an abnormal connection between two organs)
  • Grown failure (in children)
  • Weight loss

Some of the more common signs and other conditions that may occur in people with Crohn’s disease are:

These other signs, symptoms, complications, and extraintestinal manifestations of Crohn’s disease can occur because the effects of the disease reach throughout the body. 

What Causes Crohn's Disease?

No single accepted theory explains the cause of Crohn’s disease (or other forms of IBD). However, one general theory is that in people with genes for IBD, the immune system reacts to something in the digestive tract and causes inflammation.

Environmental factors: Genetics don’t tell the entire story of why some people develop Crohn’s disease and others don’t. It’s thought that outside factors also play a role. What exactly these things are is not settled science, but some are better studied than others.

A few of the potential environmental risk factors include:

  • Air pollution
  • Antibiotic use
  • Diet
  • Geography (IBD is more common in developed countries)
  • Low vitamin D levels
  • Nonsteroidal anti-inflammatory drug (NSAID) use, such as Advil (ibuprofen) or Aleve (naproxen)

Genetics: Some genes are found more commonly in people with Crohn’s disease. However, not all family members don’t always go on to develop a form of IBD. This is because the causes of Crohn’s disease are partly genetic and partly due to environmental factors. 

Immune system changes: Crohn’s disease is considered an immune-mediated condition, meaning the immune system, which is supposed to protect the body from germs and toxins, reacts abnormally, leading to digestive system inflammation. This immune reaction may be tied to a disruption in the gut microbiome (community of microbes) and other factors, which may lead to the development of Crohn’s disease.

Microbiome: The digestive system is home to many different types of germs: bacteria, viruses, and fungi. People with IBD may have a different makeup of microbes than what’s considered normal. A disturbance in the balance of the microbiome (called dysbiosis) may be a part of the development of IBD and how the disease continues.

Smoking: People who smoke might have twice the risk of developing Crohn’s disease. Risks also include secondhand smoke and being exposed to secondhand smoke at a young age. Some research has also shown that people with Crohn’s disease who are exposed to cigarette smoke have more aggressive disease with a greater need for surgery.

What Causes Crohn’s to Flare Up?

Crohn's disease goes through periods of active disease (flare-up) and periods of fewer symptoms and possible remission. What causes Crohn's disease to flare is different from person to person. However, some common factors causing or adding to a flare-up are:

  • Antibiotics: It was long thought that antibiotics could trigger an IBD flare-up. However, antibiotics are sometimes used to treat IBD. Antibiotics cause a disturbance in the microbiome, which could theoretically cause an IBD flare-up.
  • Diet: Some research shows a diet that includes foods with high levels of certain fats (e.g., polyunsaturated fatty acids and saturated fats) and omega-6 fatty acids may lead to flare-ups in some people.
  • Heat waves: People with Crohn's disease have anecdotally reported a heat wave may trigger a flare. Some research has found evidence to support this claim.
  • International travel: An emerging area of study shows a small percentage of people may have a flare-up while taking a trip that includes international air travel.
  • Low vitamin D levels. People with IBD are at risk for a low level of vitamin D. The reasons for this are unclear, but some studies have shown that having low levels of vitamin D could be part of triggering a flare-up.
  • NSAIDs: It was long thought that taking NSAIDs will lead to flare-ups, but the the effect is not as great as some earlier studies showed.
  • Smoking: Smoking cigarettes may lead to a flare-up of Crohn's disease.
  • Stopping medications: For those who take medications to keep the inflammation in check, not having access to those drugs for a time, or missing doses, could lead to a flare-up. One study showed this trigger might have the biggest effect on causing symptoms.
  • Stress: Stress doesn't cause IBD, but a stressful event could lead to an uptick in symptoms.

How Crohn's Disease Is Diagnosed

No single test can diagnose Crohn’s disease. This form of IBD is usually diagnosed using results from several different tests and taking signs and symptoms into account. The list of potential tests is long, however, not every test will be needed in everyone.

A colonoscopy in which biopsies (tissue samples) are taken is usually the test that offers the most information and helps in making a diagnosis. This procedure is done by inserting a thin, flexible tube into the rectum and up through the colon.

Other tests may be performed to support the diagnosis, rule out other issues, and look for any complications. Tests may include:

  • Barium enema: An X-ray is taken after a contrast solution is inserted via an enema (an injection of fluids) into the lower digestive tract to aid in seeing anything abnormal in the lower bowel.
  • Complete blood count (CBC): This blood test includes red and white blood cell counts. A low red blood cell count could indicate anemia and a high white blood cell count could indicate inflammation.
  • Fecal occult blood test: This test of stool (fecal matter) looks for blood that can’t be seen with the naked eye.
  • Electrolyte panel: This blood test measures electrolytes (charged minerals), which may be affected by chronic diarrhea.
  • Liver function tests: This blood test can show if some indicators of liver function are unbalanced.
  • Sigmoidoscopy: A thin tube with a light on the end is inserted into the rectum to look at the rectum and the first part of the colon, the sigmoid colon. 
  • Upper endoscopy: A thin, flexible tube is inserted into the mouth and down through the esophagus to look at the stomach and the first part of the small intestine.
  • Upper gastrointestinal (upper GI) series: This type of X-ray looks at the upper digestive tract.
  • X-rays: While they're not used as often since there now are more accurate imaging tests, a plain abdominal X-ray might be used in some circumstances to aid in diagnosis.

Crohn’s Disease Treatment

Crohn’s disease is treated in a variety of ways, using medication, surgery, and changes to diet and lifestyle. Because the disease affects people in such an individual way, there’s no one treatment plan that’s used for everyone. Instead, healthcare providers and patients work together to create a plan that will be the best fit.


Several different types of medications are approved to treat Crohn’s disease. Sometimes more than one drug is prescribed, especially during a flare-up of the disease. 

Medications include:


Surgery is a valid treatment option for Crohn’s disease. The type of surgery used will depend on where the disease is located in the intestine and the goals of treatment. These include:

  • Ostomy surgery: Ostomy surgery creates a stoma. A small section of the intestine is brought through the wall of the abdomen so stool may leave the body through the stoma. An appliance is worn over the stoma to collect stool and is emptied several times a day.
  • Proctocolectomy (ileoanal anastomosis, straight pull-through): In this surgery, the large intestine is removed. The end of the small intestine is then connected to the anus. Stool leaves the body through the anus.
  • Resection surgery: A section of the small or large intestine that is affected by Crohn’s disease is removed and the two healthy ends of the intestine are reattached. This is the most common type of surgery done for Crohn’s disease.
  • Strictureplasty: When the inside of the small or large intestine becomes too narrow in a section, one of several surgical techniques are used to widen it again.

Lifestyle Changes

Multiple lifestyle changes might be used to help manage Crohn’s disease. People work with their healthcare providers to understand which factors will be effective while also fitting into their lifestyle.

Lifestyle changes that have some evidence for their use in managing Crohn’s disease include:

  • Complementary and alternative medicine (CAM), such as curcumin supplements or acupuncture
  • Lowering stress
  • Increasing activity level
  • Increasing dietary fiber while in remission
  • Stopping smoking

How Diet Impacts Crohn's Disease

Diet is a major topic of study and discussion for people with Crohn’s disease. However, no one diet has been identified as being useful for everyone with the condition. Every person will have their own diet needs, which will change as they go through periods of active disease and remission. 

Ask for a referral to a dietitian who specializes in digestive conditions and can help people with IBD. Unfortunately, though, dietitians are in high demand and are not available to everyone, especially in underserved communities.

If you are unable to get individualized dietary guidance, you may wish to follow a Mediterranean diet . This diet emphasizes whole grains, fruits, vegetables, nuts, olive oil, and fish, with fewer servings of saturated fat, refined sugars, and meat.

Some of the diets that are under study or have been used by people with Crohn’s disease include: 

Enteral nutrition is liquid nutrition, which may be in the form of drinks or tube feeding.

Can Crohn’s Go Into Remission?

Crohn’s can go into remission, though there are various definitions of remission. They differ depending on the criteria used or the goals of the patient. Remission is often thought of as a time with few or no symptoms, but there is more to the story.

Clinical remission is when a person has few or no signs or symptoms of the disease. However, a person can feel well but still have inflammation in their body. This inflammation can cause complications months or years in the future.

For that reason, gastroenterologists and other healthcare providers may look for other types of remission, as well as clinical remission. 

Types of remission that may be discussed in relation to Crohn’s disease may include: 

  • Biochemical remission:  Blood or stool tests show no disease markers.
  • Clinical remission: Few or no signs or symptoms of the disease are reported by the person with IBD.
  • Endoscopic remission: The lining of the digestive system doesn’t show any inflammation.
  • Histologic remission: Biopsies taken during endoscopy show no inflammation.
  • Surgical remission: The absence of symptoms after having surgery to treat the disease.

Rates of Remission In Crohn's Disease

One of the more influential studies done on remission in Crohn’s disease showed that about 30% of people with Crohn's were in deep remission (clinical remission, biochemical remission and mucosal healing) at the start of the trial. Another 40% were in endoscopic remission.

Tips for Living With Crohn’s Disease

Living with Crohn’s disease will mean focusing on a lifestyle that will help prevent flare-ups and limit the potential for complications. As treatments for Crohn’s disease improve, more people can get effective care early in the disease course.

It may not always be possible to avoid flare-ups. However, getting regular care from a specialist and following a management plan that includes diet, lifestyle, and medications may help. 

Some of the practical measures you can take to help manage the disease and also give yourself a degree of control include:

  • Finding the right medication and staying on schedule
  • Following the diet that best helps in avoiding symptoms
  • Getting enough quality sleep
  • Getting regular, low-impact exercise
  • Keeping a journal or a log of signs and symptoms to look for patterns
  • Lowering stress levels
  • Practicing mindfulness and/or meditation
  • Staying hydrated

People will want to talk with their healthcare providers about how to achieve their goals. In the IBD space, this is called treat to target. A person and their provider should together decide on how treatment can help reach milestones. This could mean anything from going to the bathroom fewer times a day to having less pain to achieving long-term remission.

Outlook for Crohn’s Disease

Receiving a diagnosis of Crohn’s disease can bring on a host of emotions and worries. It’s helpful to know that there are many treatment options already, research is ongoing, and more is being understood all the time.

Medications are an important tool in the management of Crohn’s, and the pipeline of new medications and therapies is strong. Multiple drugs across many different classes of medications are being studied for use in Crohn’s disease.

Lifestyle factors and mental health are now also taking a larger role in the discussion around disease management. Diet, lifestyle, sexual health, and quality of life are being studied and discussed openly. Healthcare providers are available who specialize in IBD and can help people develop a holistic plan to manage Crohn’s disease from day to day.

With all that in mind, it is possible to live a full life while managing Crohn’s disease effectively and avoiding complications.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.