Crohn’s Disease

National Digestive Diseases Information Clearinghouse

U.S. Department 

of Health and 

Human Services

NATIONAL 

INSTITUTES 

OF HEALTH

What is Crohn’s disease?

Crohn’s disease is an ongoing disorder that 

causes inflammation of the digestive tract, 

also referred to as the gastrointestinal (GI) 

tract. Crohn’s disease can affect any area of 

the GI tract, from the mouth to the anus, but 

it most commonly affects the lower part of 

the small intestine, called the ileum. The 

swelling extends deep into the lining of the 

affected organ. The swelling can cause pain 

and can make the intestines empty frequently, resulting in diarrhea.

Crohn’s disease is an inflammatory bowel 

disease, the general name for diseases that 

cause swelling in the intestines. Because the 

symptoms of Crohn’s disease are similar to 

other intestinal disorders, such as irritable 

bowel syndrome and ulcerative colitis, it can 

be difficult to diagnose. Ulcerative colitis 

causes inflammation and ulcers in the top 

layer of the lining of the large intestine. In 

Crohn’s disease, all layers of the intestine 

may be involved, and normal healthy bowel 

can be found between sections of diseased 

bowel.

Crohn’s disease affects men and women 

equally and seems to run in some families. 

About 20 percent of people with Crohn’s 

disease have a blood relative with some form 

of inflammatory bowel disease, most often a 

brother or sister and sometimes a parent or 

child. Crohn’s disease can occur in people of 

all age groups, but it is more often diagnosed 

in people between the ages of 20 and 30. 

People of Jewish heritage have an increased 

risk of developing Crohn’s disease, and

African Americans are at decreased risk for 

developing Crohn’s disease.

Crohn’s disease may also be called ileitis 

or enteritis.

The digestive system

What causes Crohn’s 

disease?

Several theories exist about what causes 

Crohn’s disease, but none have been proven. 

The human immune system is made from 

cells and different proteins that protect 

people from infection. The most popular 

theory is that the body’s immune system 

reacts abnormally in people with Crohn’s 

disease, mistaking bacteria, foods, and other

Mouth

Esophagus

Stomach

Small 

intestine

Anus

Rectum

Ileum

Large intestine

(colon)
 

 

substances for being foreign. The immune 

system’s response is to attack these “invaders.” During this process, white blood cells 

accumulate in the lining of the intestines, 

producing chronic inflammation, which leads 

to ulcerations and bowel injury. 

Scientists do not know if the abnormality 

in the functioning of the immune system 

in people with Crohn’s disease is a cause, 

or a result, of the disease. Research shows 

that the inflammation seen in the GI tract of 

people with Crohn’s disease involves several 

factors: the genes the patient has inherited, 

the immune system itself, and the environment. Foreign substances, also referred to 

as antigens, are found in the environment. 

One possible cause for inflammation may 

be the body’s reaction to these antigens, or 

that the antigens themselves are the cause 

for the inflammation. Scientists have found 

that high levels of a protein produced by the 

immune system, called tumor necrosis factor 

(TNF), are present in people with Crohn’s 

disease. 

What are the symptoms? 

The most common symptoms of Crohn’s 

disease are abdominal pain, often in the 

lower right area, and diarrhea. Rectal bleeding, weight loss, arthritis, skin problems, and 

fever may also occur. Bleeding may be serious and persistent, leading to anemia. Children with Crohn’s disease may suffer delayed 

development and stunted growth. The range 

and severity of symptoms varies. 

How is Crohn’s disease 

diagnosed? 

A thorough physical exam and a series of 

tests may be required to diagnose Crohn’s 

disease. 

Blood tests may be done to check for anemia, which could indicate bleeding in the 

intestines. Blood tests may also uncover a 

high white blood cell count, which is a sign 

of inflammation somewhere in the body. 

By testing a stool sample, the doctor can 

tell if there is bleeding or infection in the 

intestines. 

The doctor may do an upper GI series to 

look at the small intestine. For this test, 

the person drinks barium, a chalky solution that coats the lining of the small intestine, before x rays are taken. The barium 

shows up white on x-ray film, revealing 

inflammation or other abnormalities in 

the intestine. If these tests show Crohn’s 

disease, more x rays of both the upper and 

lower digestive tract may be necessary to see 

how much of the GI tract is affected by the 

disease. 

The doctor may also do a visual exam of the 

colon by performing either a sigmoidoscopy 

or a colonoscopy. For both of these tests, the 

doctor inserts a long, flexible, lighted tube 

linked to a computer and TV monitor into 

the anus. A sigmoidoscopy allows the doctor 

to examine the lining of the lower part of the 

large intestine, while a colonoscopy allows 

the doctor to examine the lining of the entire 

large intestine. The doctor will be able to see 

any inflammation or bleeding during either 

2 Crohn’s Disease 
 

of these exams, although a colonoscopy is 

usually a better test because the doctor can 

see the entire large intestine. The doctor 

may also do a biopsy, which involves taking a 

sample of tissue from the lining of the intestine to view with a microscope. 

What are the complications 

of Crohn’s disease? 

The most common complication is blockage 

of the intestine. Blockage occurs because 

the disease tends to thicken the intestinal 

wall with swelling and scar tissue, narrowing the passage. Crohn’s disease may also 

cause sores, or ulcers, that tunnel through 

the affected area into surrounding tissues, 

such as the bladder, vagina, or skin. The 

areas around the anus and rectum are often 

involved. The tunnels, called fistulas, are 

a common complication and often become 

infected. Sometimes fistulas can be treated 

with medicine, but in some cases they may 

require surgery. In addition to fistulas, small 

tears called fissures may develop in the lining 

of the mucus membrane of the anus. 

Nutritional complications are common in 

Crohn’s disease. Deficiencies of proteins, 

calories, and vitamins are well documented. 

These deficiencies may be caused by inadequate dietary intake, intestinal loss of 

protein, or poor absorption, also referred to 

as malabsorption. 

Other complications associated with Crohn’s 

disease include arthritis, skin problems, 

inflammation in the eyes or mouth, kidney 

stones, gallstones, or other diseases of the 

liver and biliary system. Some of these problems resolve during treatment for disease 

in the digestive system, but some must be 

treated separately. 

What is the treatment for 

Crohn’s disease? 

Treatment may include drugs, nutrition 

supplements, surgery, or a combination 

of these options. The goals of treatment 

are to control inflammation, correct nutritional deficiencies, and relieve symptoms 

like abdominal pain, diarrhea, and rectal 

bleeding. At this time, treatment can help 

control the disease by lowering the number of times a person experiences a recurrence, but there is no cure. Treatment for 

Crohn’s disease depends on the location and 

severity of disease, complications, and the 

person’s response to previous medical treatments when treated for recurring symptoms. 

Some people have long periods of remission, 

sometimes years, when they are free of symptoms. However, the disease usually recurs 

at various times over a person’s lifetime. 

This changing pattern of the disease means 

one cannot always tell when a treatment has 

helped. Predicting when a remission may 

occur or when symptoms will return is not 

possible. 

Someone with Crohn’s disease may need 

medical care for a long time, with regular 

doctor visits to monitor the condition. 

Drug Therapy 

Anti-inflammation drugs. Most people are 

first treated with drugs containing mesalamine, a substance that helps control inflammation. Sulfasalazine is the most commonly 

used of these drugs. Patients who do not 

benefit from it or who cannot tolerate it 

may be put on other mesalamine-containing 

drugs, generally known as 5-ASA agents, 

3 Crohn’s Disease 
 

 

such as Asacol, Dipentum, or Pentasa. Possible side effects of mesalamine-containing 

drugs include nausea, vomiting, heartburn, 

diarrhea, and headache. 

Cortisone or steroids. Cortisone drugs 

and steroids—called corticosteriods— 

provide very effective results. Prednisone 

is a common generic name of one of the 

drugs in this group of medications. In the 

beginning, when the disease is at its worst, 

prednisone is usually prescribed in a large 

dose. The dosage is then lowered once 

symptoms have been controlled. These 

drugs can cause serious side effects, including greater susceptibility to infection. 

Immune system suppressors. Drugs that 

suppress the immune system are also used 

to treat Crohn’s disease. Most commonly 

prescribed are 6-mercaptopurine or a related 

drug, azathioprine. Immunosuppressive 

agents work by blocking the immune reaction that contributes to inflammation. These 

drugs may cause side effects like nausea, 

vomiting, and diarrhea and may lower a person’s resistance to infection. When patients 

are treated with a combination of corticosteroids and immunosuppressive drugs, the dose 

of corticosteroids may eventually be lowered. 

Some studies suggest that immunosuppressive drugs may enhance the effectiveness of 

corticosteroids. 

Infliximab (Remicade). This drug is the 

first of a group of medications that blocks 

the body’s inflammation response. The U.S. 

Food and Drug Administration approved the 

drug for the treatment of moderate to severe 

Crohn’s disease that does not respond to 

standard therapies (mesalamine substances, 

corticosteroids, immunosuppressive agents) 

and for the treatment of open, draining fistulas. Infliximab, the first treatment approved 

specifically for Crohn’s disease, is an antiTNF substance. Additional research will 

need to be done in order to fully understand 

the range of treatments Remicade may offer 

to help people with Crohn’s disease. 

Antibiotics. Antibiotics are used to treat 

bacterial overgrowth in the small intestine 

caused by stricture, fistulas, or prior surgery. 

For this common problem, the doctor may 

prescribe one or more of the following 

antibiotics: ampicillin, sulfonamide, cephalosporin, tetracycline, or metronidazole. 

Antidiarrheal and fluid replacements. 

Diarrhea and crampy abdominal pain are 

often relieved when the inflammation subsides, but additional medication may also be 

necessary. Several antidiarrheal agents could 

be used, including diphenoxylate, loperamide, and codeine. Patients who are dehydrated because of diarrhea will be treated 

with fluids and electrolytes. 

Nutrition Supplementation 

The doctor may recommend nutritional 

supplements, especially for children whose 

growth has been slowed. Special highcalorie liquid formulas are sometimes 

used for this purpose. A small number of 

patients may need to be fed intravenously 

for a brief time through a small tube inserted 

into the vein of the arm. This procedure can 

help patients who need extra nutrition temporarily, those whose intestines need to rest, 

or those whose intestines cannot absorb 

enough nutrition from food. There are no 

known foods that cause Crohn’s disease. 

However, when people are suffering a flare 

in disease, foods such as bulky grains, hot 

spices, alcohol, and milk products may 

increase diarrhea and cramping. 

4 Crohn’s Disease 
 

Surgery 

Two-thirds to three-quarters of patients with 

Crohn’s disease will require surgery at some 

point in their lives. Surgery becomes necessary when medications can no longer control 

symptoms. Surgery is used either to relieve 

symptoms that do not respond to medical 

therapy or to correct complications such as 

blockage, perforation, abscess, or bleeding 

in the intestine. Surgery to remove part of 

the intestine can help people with Crohn’s 

disease, but it is not a cure. Surgery does not 

eliminate the disease, and it is not uncommon for people with Crohn’s disease to have 

more than one operation, as inflammation 

tends to return to the area next to where the 

diseased intestine was removed. 

Some people who have Crohn’s disease in 

the large intestine need to have their entire 

colon removed in an operation called a 

colectomy. A small opening is made in the 

front of the abdominal wall, and the tip of 

the ileum, which is located at the end of 

the small intestine, is brought to the skin’s 

surface. This opening, called a stoma, is 

where waste exits the body. The stoma is 

about the size of a quarter and is usually 

located in the right lower part of the abdomen near the beltline. A pouch is worn over 

the opening to collect waste, and the patient 

empties the pouch as needed. The majority 

of colectomy patients go on to live normal, 

active lives. 

Sometimes only the diseased section of intestine is removed and no stoma is needed. In 

this operation, the intestine is cut above and 

below the diseased area and reconnected. 

Because Crohn’s disease often recurs after 

surgery, people considering surgery should 

carefully weigh its benefits and risks compared with other treatments. Surgery may 

not be appropriate for everyone. People 

faced with this decision should get as much 

information as possible from doctors; nurses 

who work with colon surgery patients, called 

enterostomal therapists; and other patients. 

Patient advocacy organizations can suggest support groups and other information 

resources. (See For More Information on 

page 7 for the names of such organizations.) 

People with Crohn’s disease may feel well 

and be free of symptoms for substantial 

spans of time when their disease is not active. 

Despite the need to take medication for long 

periods of time and occasional hospitalizations, most people with Crohn’s disease are 

able to hold jobs, raise families, and function 

successfully at home and in society. 

5 Crohn’s Disease 
 

 

Can diet control Crohn’s 

disease? 

People with Crohn’s disease often experience a decrease in appetite, which can affect 

their ability to receive the daily nutrition 

needed for good health and healing. In 

addition, Crohn’s disease is associated with 

diarrhea and poor absorption of necessary 

nutrients. No special diet has been proven 

effective for preventing or treating Crohn’s 

disease, but it is very important that people 

who have Crohn’s disease follow a nutritious 

diet and avoid any foods that seem to worsen 

symptoms. There are no consistent dietary 

rules to follow that will improve a person’s 

symptoms. 

People should take vitamin supplements only 

on their doctor’s advice. 

Can stress make Crohn’s 

disease worse? 

There is no evidence showing that stress 

causes Crohn’s disease. However, people 

with Crohn’s disease sometimes feel 

increased stress in their lives from having 

to live with a chronic illness. Some people 

with Crohn’s disease also report that they 

experience a flare in disease when they are 

experiencing a stressful event or situation. 

There is no type of person that is more likely 

to experience a flare in disease than another 

when under stress. For people who find 

there is a connection between their stress 

level and a worsening of their symptoms, 

using relaxation techniques, such as slow 

breathing, and taking special care to eat well 

and get enough sleep, may help them feel 

better. 

Is pregnancy safe for women 

with Crohn’s disease? 

Research has shown that the course of pregnancy and delivery is usually not impaired 

in women with Crohn’s disease. Even so, 

women with Crohn’s disease should discuss 

the matter with their doctors before pregnancy. Most children born to women with 

Crohn’s disease are unaffected. Children 

who do get the disease are sometimes more 

severely affected than adults, with slowed 

growth and delayed sexual development in 

some cases. 

Hope through Research 

The National Institute of Diabetes and 

Digestive and Kidney Diseases (NIDDK) 

conducts and supports research into many 

kinds of digestive disorders, including 

Crohn’s disease. Several clinical trials 

are currently evaluating the efficacy and 

safety of different therapies for the treatment 

of Crohn’s disease. 

Participants in clinical trials can play a more 

active role in their own health care, gain 

access to new research treatments before 

they are widely available, and help others 

by contributing to medical research. For 

information about current studies, visit 

www.ClinicalTrials.gov.

6 Crohn’s Disease 
7 Crohn’s Disease

For More Information

Crohn’s & Colitis Foundation of America

386 Park Avenue South, 17th Floor 

New York, NY 10016 

Phone: 1–800–932–2423 or 212–685–3440 

Email: info@ccfa.org 

Internet: www.ccfa.org

Reach Out for Youth with Ileitis and 

Colitis, Inc.

P.O. Box 857 

Bellmore, NY 11710 

Phone: 631–293–3102 

Email: info@reachoutforyouth.org 

Internet: www.reachoutforyouth.org

United Ostomy Associations of America, Inc.

P.O. Box 512 

Northfield, MN 55057–0512 

Phone: 1–800–826–0826 

Email: info@ostomy.org 

Internet: www.ostomy.org

Acknowledgments

Publications produced by the Clearinghouse 

are carefully reviewed by both NIDDK 

scientists and outside experts. This publication was reviewed by the Crohn’s & Colitis 

Foundation of America.

You may also find additional information about this 

topic by visiting MedlinePlus at www.medlineplus.gov.

This publication may contain information about 

medications. When prepared, this publication 

included the most current information available. 

For updates or for questions about any medications, 

contact the U.S. Food and Drug Administration tollfree at 1–888–INFO–FDA (1–888–463–6332) or visit 

www.fda.gov. Consult your health care provider for 

more information.

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If a product is not mentioned, the omission does not 

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U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES

National Institutes of Health

NIH Publication No. 06–3410

February 2006

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