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 a disease that causes 

inflammation, or swelling, and irritation of 

any part of the digestive tract—also called 

the gastrointestinal (GI) tract. The part 

most commonly affected is the end part of 

the small intestine, called the ileum. 

The GI tract is a series of hollow organs 

joined in a long, twisting tube from the 

mouth to the anus. The movement of muscles in the GI tract, along with the release of 

hormones and enzymes, allows for the digestion of food. 

In Crohn’s disease, inflammation extends 

deep into the lining of the affected part of 

the GI tract. Swelling can cause pain and can 

make the intestine—also called the bowel— 

empty frequently, resulting in diarrhea. 

Chronic—or long-lasting—inflammation may 

produce scar tissue that builds up inside the 

intestine to create a stricture. A stricture 

is a narrowed passageway that can slow the 

movement of food through the intestine, 

causing pain or cramps. 

Crohn’s disease is an inflammatory bowel 

disease (IBD), the general name for diseases 

that cause inflammation and irritation in the 

intestines. Crohn’s disease can be difficult to 

diagnose because its symptoms are similar to 

other intestinal disorders, such as ulcerative 

colitis and other IBDs, and irritable bowel 

syndrome. For example, ulcerative colitis 

and Crohn’s disease both cause abdominal 

pain and diarrhea. 

Crohn’s disease may also be called ileitis or 

enteritis. 

Esophagus 

Stomach 

Small 

intestine 

Anus 

Rectum 

Ileum 

Colon 

The GI tract 
 

 

Who gets Crohn’s disease? 

Crohn’s disease affects men and women 

equally and seems to run in some families. 

People with Crohn’s disease may have a 

biological relative—most often a brother 

or sister—with some form of IBD. Crohn’s 

disease occurs in people of all ages, but it 

most commonly starts in people between the 

ages of 13 and 30.1 Men and women who 

smoke are more likely than nonsmokers to 

develop Crohn’s disease. People of Jewish 

heritage have an increased risk of developing Crohn’s disease, and African Americans 

have a decreased risk. 

What causes Crohn’s 

disease? 

The cause of Crohn’s disease is unknown, 

but researchers believe it is the result of an 

abnormal reaction by the body’s immune 

system. Normally, the immune system 

protects people from infection by identifying and destroying bacteria, viruses, or other 

potentially harmful foreign substances. 

Researchers believe that in Crohn’s disease 

the immune system attacks bacteria, foods, 

and other substances that are actually harmless or beneficial. During this process, white 

blood cells accumulate in the lining of the 

intestines, producing chronic inflammation, 

which leads to ulcers, or sores, and injury to 

the intestines. 

1Sauer CG, Kugathasan S. Pediatric inflammatory 

bowel disease: highlighting pediatric differences 

in IBD. Gastroenterology Clinics of North America. 

2009;38(4):611–628. 

Researchers 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. 

However, researchers do not know whether 

increased levels of TNF and abnormal functioning of the immune system are causes or 

results of Crohn’s disease. Research shows 

that the inflammation seen in the GI tract of 

people with Crohn’s disease involves several 

factors: the genes the person has inherited, the person’s immune system, and the 

environment. 

What are the symptoms of 

Crohn’s disease? 

The most common symptoms of Crohn’s disease are abdominal pain, often in the lower 

right area, and diarrhea. Rectal bleeding, 

weight loss, and fever may also occur. Bleeding may be serious and persistent, leading 

to anemia—a condition in which red blood 

cells are fewer or smaller than normal, which 

means less oxygen is carried to the body’s 

cells. 

The range and severity of symptoms varies. 

2 Crohn’s Disease 
 

How is Crohn’s disease 

diagnosed? 

A doctor will perform a thorough physical 

exam and schedule a series of tests to diagnose Crohn’s disease. 

• Blood tests can be used to look for 

anemia caused by bleeding. Blood tests 

may also uncover a high white blood cell 

count, which is a sign of inflammation 

or infection somewhere in the body. 

Blood is drawn at a health care provider’s office or commercial facility and 

sent to a lab for analysis. 

• Stool tests are commonly done to rule 

out other causes of GI diseases, such as 

infection. Stool tests can also show if 

there is bleeding in the intestines. The 

doctor will give the person a container 

for catching and storing the stool. The 

sample is returned to the doctor or a 

commercial facility and sent to a lab for 

analysis. 

The tests below are usually performed at a 

hospital or outpatient center by a gastroenterologist, a doctor who specializes in digestive diseases, or a radiologist, a doctor who 

specializes in medical imaging. 

• Flexible sigmoidoscopy and colonoscopy. These tests are used to help 

diagnose Crohn’s disease and determine 

how much of the GI tract is affected. 

Colonoscopy is the most commonly 

used test to specifically diagnose 

Crohn’s disease. Colonoscopy is used to 

view the ileum, rectum, and the entire 

colon, while flexible sigmoidoscopy is 

used to view just the lower colon and 

rectum. For both tests, a health care 

provider will provide written bowel prep 

instructions to follow at home before 

the test. The person may be asked to 

follow a clear liquid diet for 1 to 3 days 

before the test. A laxative may be 

required the night before the test. One 

or more enemas may be required the 

night before and about 2 hours before 

the test. 

For either test, the person will lie on 

a table while the doctor inserts a flexible tube into the anus. A small camera on the tube sends a video image 

of the intestinal lining to a computer 

screen. The doctor can see inflammation, bleeding, or ulcers on the colon 

wall. The doctor may also perform a 

biopsy by snipping a bit of tissue from 

the intestinal lining. The person will 

not feel the biopsy. The doctor will 

look at the tissue with a microscope to 

confirm the diagnosis. For a colonoscopy, a light sedative—and possibly pain 

medication—helps people relax. 

Cramping or bloating may occur during the first hour after the test. Driving 

is not permitted for 24 hours after a 

colonoscopy to allow the sedative time 

to wear off. Before the appointment, 

people should make plans for a ride 

home. Full recovery is expected by the 

next day. 

3 Crohn’s Disease 
 

The tests below are performed at a hospital 

or outpatient center by an x-ray technician, and the images are interpreted by a 

radiologist. 

• Computerized tomography (CT) scan. 

CT scans use a combination of x rays 

and computer technology to create 

three-dimensional (3-D) images. For 

a CT scan, the person may be given a 

solution to drink and an injection of a 

special dye, called contrast medium. 

CT scans require the person to lie on 

a table that slides into a tunnel-shaped 

device where the x rays are taken. 

CT scans can be used to help diagnose 

Crohn’s disease. Children may be given 

a sedative to help them fall asleep for 

the test. 

• Upper GI series. An upper GI series 

may be done to look at the small intestine. No eating or drinking is allowed 

for 8 hours before the procedure, if 

possible. During the procedure, the 

person will stand or sit in front of an 

x-ray machine and drink barium, a 

chalky liquid. Children may be given a 

sedative to help them fall asleep for the 

test. Children who are sedated will lie 

on a table for the test. Barium coats the 

small intestine, making signs of Crohn’s 

disease show up more clearly on x rays. 

A person may experience bloating and 

nausea for a short time after the test. 

For several days afterward, barium 

liquid in the GI tract causes stools to be 

white or light colored. A health care 

provider will provide specific instructions about eating and drinking after the 

test. 

• Lower GI series. A lower GI series may 

be done to look at the large intestine. A 

health care provider may provide written bowel prep instructions to follow 

at home before the test. The person 

may be asked to follow a clear liquid 

diet for 1 to 3 days before the procedure. A laxative or enema may be used 

before the test. A laxative is medication that loosens stool and increases 

bowel movements. An enema involves 

flushing water, laxative, or sometimes a 

mild soap solution into the anus using a 

special squirt bottle. 

Children may be given a sedative to 

help them fall asleep for the test. For 

the test, the person will lie on a table 

while the doctor inserts a flexible tube 

into the person’s anus. The large intestine is filled with barium, making signs 

of Crohn’s disease show up more clearly 

on x rays. 

For several days afterward, traces of 

barium liquid in the large intestine 

cause stools to be white or light colored. 

Enemas and repeated bowel movements 

may cause anal soreness. A health care 

provider will provide specific instructions about eating and drinking after the 

test. 

4 Crohn’s Disease 
 

What are the complications 

of Crohn’s disease? 

The most common complication of Crohn’s 

disease is an intestinal blockage caused by 

thickening of the intestinal wall because of 

swelling and scar tissue. Crohn’s disease 

may also cause ulcers that tunnel through 

the affected area into surrounding tissues. 

The tunnels, called fistulas, are a common 

complication—especially in the areas around 

the anus and rectum—and often become 

infected. Most fistulas can be treated with 

medication, but some may require surgery. 

In addition to fistulas, small tears called 

fissures may develop in the lining of the 

mucus membrane of the anus. The health 

care provider may prescribe a topical cream 

and may suggest soaking the affected area in 

warm water. 

Some Crohn’s disease complications occur 

because the diseased area of intestine does 

not absorb nutrients effectively, resulting 

in deficiencies of proteins, calories, and 

vitamins. 

People with Crohn’s disease often have anemia, which can be caused by the disease itself 

or by iron deficiency. Anemia may make a 

person feel tired. Children with Crohn’s disease may fail to grow normally and may have 

low height for their age. 

People with Crohn’s disease, particularly if 

they have been treated with steroid medications, may have weakness of their bones— 

called osteoporosis or osteomalacia. 

Some people with Crohn’s disease may have 

restless legs syndrome—extreme leg discomfort a person feels while sitting or lying 

down.2 Some of these problems clear up 

during treatment for Crohn’s disease, but 

some must be treated separately. 

Other complications include arthritis, skin 

problems, inflammation in the eyes or 

mouth, kidney stones, gallstones, or diseases 

related to liver function. 

What is the treatment for 

Crohn’s disease? 

Treatment may include medications, surgery, 

nutrition supplementation, or a combination 

of these options. The goals of treatment are 

to control inflammation, correct nutritional 

deficiencies, and relieve symptoms such as 

abdominal pain, diarrhea, and rectal bleeding. Treatment for Crohn’s disease depends 

on its location, severity, and complications. 

Treatment can help control Crohn’s disease 

and make recurrences less frequent, but no 

cure exists. Someone with Crohn’s disease 

may need long-lasting medical care and regular doctor visits to monitor the condition. 

Some people have long periods—sometimes 

years—of remission when they are free of 

symptoms, and predicting when a remission 

may occur or when symptoms will return 

is not possible. This changing pattern of 

the disease makes it difficult to be certain a 

treatment has helped. 

Despite possible hospitalizations and the 

need to take medication for long periods of 

time, most people with Crohn’s disease have 

full lives—balancing families, careers, and 

activities. 

2Weinstock LB, Bosworth BP, Scherl EJ, et al. Crohn’s 

disease is associated with restless legs syndrome. 

Inflammatory Bowel Disease. 2010;16(2):275–279. 

5 Crohn’s Disease 
 

Medications 

Anti-inflammation medications. Most 

people are first treated with medications containing mesalamine, a substance that helps 

control inflammation. Sulfasalazine is the 

most commonly used of these medications. 

People who do not benefit from sulfasalazine 

or who cannot tolerate it may be put on other 

mesalamine-containing medications, known 

as 5-aminosalicylic acid (5-ASA) agents, such 

as Asacol, Dipentum, or Pentasa. Possible 

side effects of mesalamine-containing medications include nausea, vomiting, heartburn, 

diarrhea, and headache. 

Cortisone or steroids. These medications, 

also called corticosteroids, are effective at 

reducing inflammation. Prednisone and 

budesonide are generic names of two corticosteroids. During the earliest stages of 

Crohn’s disease, when symptoms are at their 

worst, corticosteroids are usually prescribed 

in a large dose. The dosage is then gradually 

lowered once symptoms are controlled. Corticosteroids can cause serious side effects, 

including greater susceptibility to infection 

and osteoporosis, or weakening of the bones. 

See the “Nutrition Supplementation” section 

for more information about preventing and 

treating osteoporosis. 

Immune system suppressors. Medications 

that suppress the immune system—called 

immunosuppressive medications—are also 

used to treat Crohn’s disease. The most 

commonly prescribed medications are 

6-mercaptopurine and azathioprine. Immunosuppressive medications work by blocking 

the immune reaction that contributes to 

inflammation. These medications may cause 

side effects such as nausea, vomiting, and 

diarrhea and may lower a person’s resistance 

to infection. Some people are treated with 

a combination of corticosteroids and immunosuppressive medications. Some studies 

suggest that immunosuppressive medications may enhance the effectiveness of 

corticosteroids. 

Biological therapies. Biological therapies 

are medications given by an injection in the 

vein, infliximab (Remicade), or an injection 

in the skin, adalimumab (HUMIRA). Biological therapies bind to TNF substances 

to block the body’s inflammation response. 

The U.S. Food and Drug Administration approved these medications for the 

treatment of moderate to severe Crohn’s 

disease that does not respond to standard 

therapies—mesalamine substances, corticosteroids, immunosuppressive medications— 

and for the treatment of open, draining 

fistulas. Some studies suggest that biological 

therapies may enhance the effectiveness of 

immunosuppressive medications. 

Antibiotics. Antibiotics are used to treat 

bacterial overgrowth in the small intestine 

caused by stricture, fistulas, or surgery. For 

this common problem, the doctor may prescribe one or more of the following antibiotics: ampicillin, sulfonamide, cephalosporin, 

tetracycline, or metronidazole. 

6 Crohn’s Disease 
 

 

Anti-diarrheal medications and fluid 

replacements. Diarrhea and abdominal 

cramps are often relieved when the inflammation subsides, but additional medication 

may be needed. Anti-diarrheal medications include diphenoxylate, loperamide, 

and codeine. People with diarrhea should 

drink plenty of fluids to prevent dehydration. 

If diarrhea does not improve, the person 

should see the doctor promptly for possible 

treatment with intravenous fluids. 

Surgery 

About two-thirds of people with Crohn’s 

disease will require surgery at some point 

in their lives.3 Surgery becomes necessary 

to relieve symptoms that do not respond to 

medical therapy or to correct complications 

such as intestinal blockage, perforation, 

bleeding, or abscess—a painful, swollen, 

pus-filled area caused by infection. Surgery 

to remove part of the intestine can help 

people with Crohn’s disease, but it does not 

eliminate the disease. People with Crohn’s 

disease commonly need more than one 

operation because inflammation tends to 

return to the area next to where the diseased 

intestine was removed. 

3Lichtenstein GR, Hanauer SB, Sandborn WJ, and 

The Practice Parameters Committee of the American 

College of Gastroenterology. Management of Crohn’s 

disease in adults. American Journal of Gastroenterology. 

2009;104(2):465–83. 

• Proctocolectomy. Some people who 

have Crohn’s disease must have a 

proctocolectomy, a procedure that is 

performed by a specialized surgeon. 

Proctocolectomy is surgery to remove 

the rectum and part of the colon or 

the entire colon. People will receive 

sedation and general anesthesia during 

surgery. Most people need to remain 

in the hospital for 1 to 2 weeks, and full 

recovery can take 4 to 6 weeks. 

• Ileostomy. During proctocolectomy, the 

surgeon also performs an ileostomy—an 

operation that attaches the ileum to an 

opening made in the abdomen called a 

stoma. The stoma is about the size of 

a quarter and is usually located in the 

lower right part of the abdomen near 

the beltline. An ostomy pouch is then 

attached to the stoma and worn outside 

the body to collect stool. The pouch 

needs to be emptied several times a 

day. A specially trained nurse will teach 

the person how to clean, care for, and 

change the ostomy pouch and how 

to protect the skin around the stoma. 

The majority of people with an ostomy 

pouch are able to live normal, active 

lives. 

• Intestinal resection surgery. Sometimes 

only the diseased section of intestine 

is removed and an ileostomy is not 

needed. Instead, the intestine is cut 

above and below the diseased area and 

the ends of the healthy sections are 

connected in an operation called an 

intestinal resection. People will receive 

sedation and general anesthesia during 

surgery. Most people need to remain 

in the hospital for several days, and full 

recovery can take 3 to 4 weeks. 

Because Crohn’s disease often recurs after 

surgery, people considering surgery should 

carefully weigh its benefits and risks compared with other treatments. People faced 

with this decision should get information 

from health care providers who routinely 

work with GI patients, including those who 

have had intestinal surgery. Patient advocacy 

organizations can suggest support groups and 

other information resources. 

7 Crohn’s Disease 
 

Nutrition Supplementation 

The health care provider may recommend 

nutritional supplements, especially for children whose growth has been slowed. Special 

high-calorie liquid formulas are sometimes 

used. A small number of people may receive 

nutrition intravenously for a brief time 

through a small tube inserted into an arm 

vein. This procedure can help people who 

need extra nutrition temporarily, such as 

those whose intestines need to rest, or those 

whose intestines cannot absorb enough nutrition from food. 

The doctor may prescribe calcium, 

vitamin D, and other medications to prevent 

or treat osteoporosis for patients taking 

corticosteroids. People should take vitamin 

supplements only after talking with their 

doctor. 

Eating, Diet, and Nutrition 

No special diet has been proven effective for 

preventing or treating Crohn’s disease, but 

it is important that people who have Crohn’s 

disease follow a nutritious diet and avoid 

any foods that seem to worsen symptoms. 

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. 

Foods do not cause Crohn’s disease, but 

foods such as bulky grains, hot spices, alcohol, and milk products may increase diarrhea 

and cramping. The health care provider may 

refer a person with Crohn’s disease to a dietitian for guidance about meal planning. 

Can smoking make Crohn’s 

disease worse? 

Studies have shown that people with Crohn’s 

disease who smoke may have more severe 

symptoms and increased complications of the 

disease, along with a need for higher doses of 

steroids and other medications. People with 

Crohn’s disease who smoke are also more 

likely to need surgery. Quitting smoking 

can greatly improve the course of Crohn’s 

disease and help reduce the risk of complications and flare ups. A health care provider 

can assist people in finding a smoking cessation specialist. 

Can stress make Crohn’s 

disease worse? 

No evidence shows that stress causes Crohn’s 

disease. However, people with Crohn’s disease sometimes feel increased stress in their 

lives because they live with a chronic illness. 

Some people with Crohn’s disease report 

having a flare up when experiencing a stressful event or situation. For people who find 

there is a connection between stress level and 

a worsening of symptoms, using relaxation 

techniques—such as slow breathing—and 

taking special care to eat well and get enough 

sleep may help them feel better. The health 

care provider may suggest a counselor or 

support group to help decrease stress for 

people with Crohn’s disease. 

8 Crohn’s Disease 
 

Is pregnancy safe for women 

with Crohn’s disease? 

Women with Crohn’s disease can become 

pregnant and have a baby. Even so, women 

with Crohn’s disease should talk with their 

health care provider before getting pregnant. 

Most children born to women with Crohn’s 

disease are not affected by the condition. 

Points to Remember 

• Crohn’s disease is a disease that causes 

inflammation, or swelling, and irritation 

of any part of the digestive tract—also 

called the gastrointestinal (GI) tract. 

• Crohn’s disease affects men and women 

equally and seems to run in some 

families. 

• The cause of Crohn’s disease is 

unknown, but researchers believe it is 

the result of an abnormal reaction by 

the immune system. 

• The most common symptoms of 

Crohn’s disease are abdominal pain and 

diarrhea. 

• A doctor can diagnose Crohn’s disease 

by performing a physical exam, blood 

and stool tests, and imaging tests such 

as a CT scan, upper GI series, lower 

GI series, flexible sigmoidoscopy, and 

colonoscopy. 

• The most common complication of 

Crohn’s disease is an intestinal blockage 

caused by thickening of the intestinal 

wall because of swelling and scar tissue. 

• Doctors treat Crohn’s disease with 

medications, surgery, nutrition supplementation, or a combination of these 

options. 

• No special diet has been proven effective for preventing or treating Crohn’s 

disease, but it is important that people 

who have Crohn’s disease follow a nutritious diet and avoid any foods that seem 

to worsen symptoms. 

• Some people with Crohn’s disease 

report having a flare up when experiencing a stressful event or situation. 

The health care provider may suggest 

a counselor or support group to help 

decrease stress for people with Crohn’s 

disease. 

• Women with Crohn’s disease can 

become pregnant and have a baby. 

Even so, women with Crohn’s disease 

should talk with their health care provider before getting pregnant. 

9 Crohn’s Disease 
 

Hope through Research 

The National Institute of Diabetes and 

Digestive and Kidney Diseases’ (NIDDK’s) 

Division of Digestive Diseases and Nutrition supports research into digestive conditions, including Crohn’s disease. NIDDK 

researchers are studying the influence of 

genetics in Crohn’s disease. More information about this study, funded under 

National Institutes of Health (NIH) project 

number 5RC1DK086502–02, can be found 

at www.projectreporter.nih.gov. NIDDK 

researchers are also studying ways to 

deliver medications directly to the site of 

inflammation that might be more effective 

than current treatments for inflammatory 

bowel disease. This study is funded under 

NIH research development grant number 

R24DK–064399. 

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. 

For More Information 

Crohn’s & Colitis Foundation of America 

386 Park Avenue South, 17th Floor 

New York, NY 10016–8804 

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.uoaa.org 

10 Crohn’s Disease 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Acknowledgments 

Publications produced by the Clearinghouse 

are carefully reviewed by both NIDDK scientists and outside experts. This publication 

was originally reviewed by the Crohn’s and 

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. 

The U.S. Government does not endorse or favor any 

specific commercial product or company. Trade, 

proprietary, or company names appearing in this 

document are used only because they are considered 

necessary in the context of the information provided. 

If a product is not mentioned, the omission does not 

mean or imply that the product is unsatisfactory. 

11 Crohn’s Disease 
 

 

 

 

 

National Digestive Diseases 

Information Clearinghouse 

2 Information Way 

Bethesda, MD 20892–3570 

Phone: 1–800–891–5389 

TTY: 1–866–569–1162 

Fax: 703–738–4929 

Email: nddic@info.niddk.nih.gov 

Internet: www.digestive.niddk.nih.gov 

The National Digestive Diseases Information 

Clearinghouse (NDDIC) is a service of the 

National Institute of Diabetes and Digestive 

and Kidney Diseases (NIDDK). The 

NIDDK is part of the National Institutes of 

Health of the U.S. Department of Health 

and Human Services. Established in 1980, 

the Clearinghouse provides information 

about digestive diseases to people with 

digestive disorders and to their families, 

health care professionals, and the public. 

The NDDIC answers inquiries, develops and 

distributes publications, and works closely 

with professional and patient organizations 

and Government agencies to coordinate 

resources about digestive diseases. 

This publication is not copyrighted. The Clearinghouse encourages users of this publication to 

duplicate and distribute as many copies as desired. 

This publication is available at 

www.digestive.niddk.nih.gov. 

U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES 

National Institutes of Health 

NIH Publication No. 12–3410 

December 2011 

The NIDDK prints on recycled paper with bio-based ink.