Crohn's Disease

What is Crohn's disease?

Crohn’s disease is a chronic, or long-lasting, disease, in which there is inflammation (irritation, swelling, or sores) in the digestive tract, most commonly the small intestine and/or the large intestine. However, it may affect any part of the gastrointestinal (GI) tract, from the mouth to the anus. It usually begins gradually and may worsen over time. It varies in intensity and may sometimes go into remission (a period with no symptoms). It may cause diarrhea, abdominal pain, or other symptoms.

What are the symptoms of Crohn's disease?

The most common symptoms of Crohn's disease are diarrhea, weight loss, and abdominal pain or cramping. Other possible symptoms include fatigue, fever, nausea, poor appetite, anemia, joint pains, eye irritation, or a skin condition called erythema nodosum with tender, red bumps under the skin. The location of the inflammation and Crohn's disease will affect what symptoms occur.

What causes Crohn's disease?

Autoimmune Disease: Crohn's disease occurs when the immune system reacts against the lining of the intestine. Normally, the immune system attacks germs, foreign substances, or cells that have become defective. If the immune system mistakenly attacks healthy cells, this is called an autoimmune disease. Crohn's disease is in autoimmune disease that involves the intestine. Other intestinal autoimmune diseases are ulcerative colitis and microscopic colitis.

Genes: Crohn's disease may run in families, indicating that the genes contribute to Crohn's disease. Many genes have been implicated in Crohn's disease, and scientists are just beginning to understand the link between specific genes and Crohn's disease. NOD2 is the most well-studied gene and is involved in immune reactions. Genes alone do not explain why a particular person gets Crohn's disease, so random or environmental factors also must play a role.

Environment: Crohn's disease is more common in smokers. There is a slight increase in the risk of developing Crohn's disease with use of antibiotics, oral contraceptives, or nonsteroidal anti-inflammatory drugs, and with a high-fat diet. The many bacteria that normally live in the intestine (the microbiome) probably have an effect on Crohn's disease. However no specific contagious bacteria or virus has ever been found to cause Crohn's disease. Stress, emotional distress, and specific foods may cause worsening of symptoms, but they do not cause Crohn's disease.

Diagnosis of Crohn’s Disease

Dr. Harary diagnoses Crohn's disease by using a combination of medical history, the physical examination, laboratory tests (on blood or stool), imaging (X-ray) tests, and colonoscopy or wireless capsule endoscopy. He will first see patients in his New York City office and then arrange for any appropriate testing. Visualization of the colon (large intestine) by colonoscopy and the small intestine by one of the following diagnostic tests is usually necessary to completely evaluate Crohn's disease. Some of the diagnostic tests that are used for Crohn's disease are:

Upper GI Series and Small Bowel Series (also known as Small Bowel Follow-Through): In this X-ray test, the patient drinks barium, which outlines the inside surfaces of the esophagus, stomach, and small intestine. X-rays are then taken to visualize these organs. The patient should not eat or drink before the test, as instructed by the radiologist (X-ray doctor). A laxative may be given after the test, and the barium usually causes light-colored stools and possibly diarrhea after the procedure.

CT Scan (Computerized Tomography): In this X-ray test, computer technology is used to create 3-dimensional views of the internal organs. The patient is usually given a solution to drink and may receive an injection of a dye - intravenous (IV) contrast. The patient lies on a table that is surrounded by a large machine that takes X-rays. There is a special type of CT scan called CT enterography that provides a better image of the small intestine by using a different oral solution to drink before the x-rays are taken. Anesthesia is not needed for CT scans. The patient should not eat or drink before the scan, as instructed by the radiologist. This test can be used for the initial diagnosis of Crohn's disease or to diagnose complications in patients with known Crohn's disease. If possible, repeated CT scans should not be done on the same patient, especially younger patients, to avoid excessive exposure to radiation. MRI does not use radiation and may be preferable when repeated scans are needed.

MRI (Magnetic Resonance Imaging): This test is similar to the CT scan, but uses magnetic fields instead of X-rays. MRI enterography is the specific type of MRI that visualizes the small intestine. Since magnetic fields are used to obtain images, there is no exposure to radiation.

Upper GI endoscopy and enteroscopy: In these tests, a thin flexible tube was passed through the mouth into the GI tract and to directly visualize the inside of the esophagus, stomach, and small intestine. Enteroscopy is similar to a simple upper GI endoscopy (see separate section under Services We Provide).

Single or Double Balloon Enteroscopy and Spiral Enteroscopy use special attachments to allow the endoscope to reach even further into the small intestine.

Colonoscopy: This test is described in the colonoscopy page of Services We Provide. It is one of the key tests used in diagnosing Crohn's disease, and Dr. Harary also uses it to assess activity of the inflammation, diagnose complications of Crohn's disease, and as a preventive screening test for cancer in Crohn's disease patients.

Wireless Capsule Endoscopy: This test visualizes the inner lining of the small intestine using a swallowed capsule that contains a camera, a radio transmitter, a light, and a battery. Dr. Albert M. Harary performs this test in his New York City office. It is described in the Wireless Capsule Endoscopy page of Services We Provide.

Complications of Crohn's disease

Intestinal obstruction: Over time, the chronic inflammation and scarring can cause narrowing of the intestine. Partial or complete obstruction can result and block food or stool from passing through the intestine. Vomiting, abdominal distention, and/or new or increased abdominal pain or symptoms of intestinal obstruction and should be promptly reported to your doctor. Complete obstruction is an emergency that often requires surgery.

Fistulas are abnormal tunnels or passages between the inside of the intestine and another organ (urinary bladder, vagina, other parts of the intestine) or the outside of the body (especially around the anus). Some fistulas can be healed with medications and diet, and some require surgery.

Ulcers are open sores that can occur anywhere in the gastrointestinal tract, from the mouth to the anus. They are a manifestation of the inflammation of Crohn's disease and are treated in the same way.

Nutritional deficiencies: the diseased intestine in Crohn's disease sometimes cannot absorb nutrients into the body, causing a lack of necessary vitamins, minerals, protein, calories, or even fluids.

Anal fissures are small tears in the lining of the anus that can cause pain or bleeding. They are usually treated with creams, diet changes, warm baths, and normalization of bowel movements, but occasionally surgery is necessary.

Inflammation outside the GI tract: Crohn's disease can cause inflammation to occur in the joints, eyes (uveitis or scleritis), the mouth, or in the skin (erythema nodosum).

Colon cancer: There is a higher risk of developing colon cancer in patients whose Crohn's disease involves the large intestine or colon. Effective long-term control of the inflammation reduces the risk. After as little as 8 years of disease, frequent colonoscopies become advisable to search for precancerous changes (dysplasia) or early cancer.

Treatment of Crohn's disease

Dr. Harary recommends 3 major approaches to treating Crohn's disease:


-bowel rest and special diets.


Medications are used to decrease inflammation and heal the intestine (induction of remission), to maintain the remission, and to control his symptoms. The following medications can be used:

Aminosalicylates (mesalamine, olsalazine, balsalazide, and sulfasalazine): These medications decrease inflammation in the intestine. They are the safest choice but are weaker than the other options, so they can be used mostly to treat mild disease or in combination with other drugs.

Antibiotics, such as ciprofloxacin and metronidazole, may benefit some Crohn's disease patients, especially those with fistulas or with infections or abscesses.

For more moderate or severe Crohn's disease, it is necessary to use stronger medications that reduce the activity of the immune system but also have more potential to cause serious side effects, especially serious infections:

Corticosteroids (also known as steroids, but not the type used by certain athletes) reduce the activity of the immune system and decrease inflammation. They include budesonide (Uceris, Entocort), prednisone, hydrocortisone, and methylprednisolone. These can be taken orally in pill form or can be applied directly to the lining of the rectum and/or lower colon in the form of suppositories or medicated enemas. They can be given intravenously in hospitalized patients. These drugs are effective for the short term in inducing a remission in Crohn’s disease, but are not safe for long-term use. Corticosteroids can produce many side effects, including a higher chance of developing infections, loss of bone calcium, death of bone tissue that can cause permanent joint problems, acne, mood swings, insomnia, high blood sugar, high blood pressure, and weight gain. Budesonide has fewer side effects than the other steroids.

Biologic therapies block certain proteins made by the immune system. They include anti-TNF (tumor necrosis factor) antibodies: Infliximab (Remicade), adalimumab (Humira) and certolizumab (Cimzia). Another new biologic drug is vedolizumab (Entyvio). These medications are the most potent available for general use. They can profoundly improve the activity of Crohn's disease. Allergic reactions, mostly skin rashes, especially with infliximab, and serious infections, such as tuberculosis, can occur. They are administered intravenously or by patients injecting themselves and are usually used for years.

Immunomodulators: 6-mercaptopurine, azathioprine, and methotrexate decrease the activity of the immune system and can be used for long-term treatment of Crohn disease, alone or in combination with biologic therapies. They can take weeks to months to start working. Like biologic drugs, they can cause serious side effects, including serious infections, pancreatitis, skin cancers, a slight increase in the risk of lymphoma (lymph node cancer), and liver injury.

NSAID’s (nonsteroidal anti-inflammatory drugs), such as ibuprofen (Motrin, Advil, etc.), naproxen (Aleve) and aspirin should be avoided, as they can worsen intestinal inflammation.

Bowel rest: In some patients with severe Crohn's disease, eliminating all oral intake, except for some clear fluids, for 1-4 weeks, can allow healing of the inflammation. Intravenous fluids and nutrition are required, and these can be administered in the hospital or in special home programs.

Diet: Very restricted diets have been shown to help patient to have Crohn's disease. Exclusive enteral nutrition therapy, in which a defined liquid formula and no other food is eaten for 4-12 weeks, can induce remission in many Crohn's disease patients. The specific carbohydrate diet (with strict restriction of grains, all sugars except for glucose, fructose, and galactose, processed meats, and most dairy products) has not been shown to consistently help Crohn's disease patients, although an occasional patient may benefit. These diets are very difficult to sustain and are probably not practical for most patients. Restricted diet therapies can cause harmful deficiencies of nutrients and should only be used under the supervision of a physician and a registered dietitian for nutritionist. In the future, new dietary therapies may be found to be beneficial, but in the meantime, unproven diet therapies are more likely to be harmful than beneficial.

Although diets containing healthy amounts of fiber are generally good, Dr. Harary advises his patients with partial small intestinal obstruction or active inflammation of the colon to minimize fiber intake.

Crohn's disease can cause nutritional deficiencies and malnutrition. Specific nutrient levels should be checked periodically by blood tests, and any deficiencies should be corrected. Maintaining a normal vitamin D level seems to keep patients in remission longer.

Surgery: Many patients with Crohn's disease eventually require surgery because symptoms are not controlled with medications, side effects of medications are too severe, bowel obstructions or fistulas develop and do not respond to medications, or life-threatening bleeding develops. Common surgical operations include opening blockages by removing the involved small intestine segment or performing a strictureplasty, drainage of abscesses (pus collections), or removal of part or all of the colon. Total removal of the colon may require the surgeon to connect the intestine to an opening in the abdomen (an ileostomy). Surgery does not cure Crohn's disease, but often eliminates the active problem and allows the patient to resume normal activities. Medications are also required after surgery to prevent or delay relapses of the Crohn's disease.