The two primary types of inflammatory bowel disease (IBD) are
These two diseases have many similarities and sometimes are difficult to distinguish from each other. However, there are several differences. For example, Crohn disease can affect almost any part of the digestive tract, whereas ulcerative colitis almost always affects only the large intestine.
The cause of inflammatory bowel disease is not known, but evidence suggests that normal intestinal bacteria inappropriately trigger an immune reaction in people with a genetic predisposition.
Inflammatory bowel disease affects people of all ages but usually begins before age 30, typically from age 14 to 24. A few people have their first attack between the ages of 50 and 70. IBD is most common among people of Northern European and Anglo-Saxon descent and is 2 to 4 times more common among Ashkenazi Jews than non-Jewish White people who live in the same region. Both sexes are equally affected. First-degree relatives (mother, father, sister, or brother) of people with IBD have a 4- to 20-fold increased risk of developing IBD. The tendency to run in families is much higher in Crohn disease than ulcerative colitis.
Symptoms of IBD
The symptoms of inflammatory bowel disease vary depending on which part of the intestine is affected and whether the person has Crohn disease or ulcerative colitis. People with Crohn disease usually have chronic diarrhea and abdominal pain. People with ulcerative colitis usually have intermittent episodes of abdominal pain and bloody diarrhea. In both diseases, people with longstanding diarrhea may lose weight and become undernourished.
Sometimes IBD can affect other parts of the body such as the joints, eyes, mouth, liver, gallbladder, and skin. IBD also increases the risk of cancer in areas of the intestine that are affected.
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Diagnosis of IBD
Stool and blood tests
Endoscopy with tissue biopsy
To make a diagnosis of inflammatory bowel disease, a doctor must first exclude other possible causes of inflammation. For example, infection with parasites or bacteria may cause inflammation. Therefore, the doctor does several tests.
Stool samples are analyzed for evidence of a bacterial or parasitic infection (acquired during travel, for example), including a type of bacterial infection (Clostridioides difficile infection Clostridioides (formerly Clostridium) difficile-Induced Colitis Clostridioides difficile (C. difficile)–induced colitis is an inflammation of the large intestine (colon) that results in diarrhea. The inflammation is caused by toxin produced... read more [formerly Clostridium difficile]) that can result from antibiotic use.
Tests may also be done to detect sexually transmitted infections of the rectum, such as gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, or throat, or the membranes that cover... read more 
, herpesvirus infection Herpes Simplex Virus (HSV) Infections Herpes simplex virus infection causes recurring episodes of small, painful, fluid-filled blisters on the skin, mouth, lips (cold sores), eyes, or genitals. This very contagious viral infection... read more 
, and chlamydial infection Chlamydia and Other Nongonococcal Infections Chlamydial infections include sexually transmitted infections of the urethra, cervix, and rectum that are caused by the bacteria Chlamydia trachomatis. These bacteria can also infect... read more 
.
Tissue samples may be taken from the lining of the digestive tract during endoscopy Endoscopy Endoscopy is an examination of internal structures using a flexible viewing tube (endoscope). In addition to examinations, doctors can use endoscopy to do biopsies and give treatment. Endoscopes... read more (an examination of the digestive tract using a viewing tube) and examined microscopically for evidence of other causes of inflammation of the colon (colitis) or inflammation of the last part of the small intestine (ileum). This removal and examination of tissue is called a biopsy.
Doctors also consider other disorders that cause similar abdominal symptoms such as irritable bowel syndrome Irritable Bowel Syndrome (IBS) Irritable bowel syndrome is a disorder of the digestive tract that causes recurring abdominal pain and constipation or diarrhea. Symptoms vary but often include lower abdominal pain, bloating... read more , ischemic colitis Ischemic Colitis Ischemic colitis is injury of the large intestine that results from an interruption of blood flow. Abdominal pain and bloody stools are common. Computed tomography is usually done, and colonoscopy... read more 
(which occurs more often in people older than 50), malabsorption syndromes Overview of Malabsorption Malabsorption syndrome refers to a number of disorders in which nutrients from food are not absorbed properly in the small intestine. Certain disorders, infections, and surgical procedures can... read more , including celiac disease Celiac Disease Celiac disease is a hereditary intolerance to gluten (a protein found in wheat, barley, and rye) that causes characteristic changes in the lining of the small intestine, resulting in malabsorption... read more 
, and certain gynecologic disorders in women. The doctor may do imaging studies, such as x-rays X-Ray Studies of the Digestive Tract X-rays often are used to evaluate digestive problems. Standard x-rays ( plain x-rays) can show some blockages or paralysis of the digestive tract, or abnormal air patterns in the abdominal cavity... read more , computed tomography Computed Tomography and Magnetic Resonance Imaging of the Digestive Tract Computed tomography (CT) and magnetic resonance imaging (MRI) scans are good tests for assessing the size and location of abdominal organs. Additionally, cancerous (malignant) or noncancerous... read more (CT), or magnetic resonance imaging Magnetic Resonance Imaging (MRI) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more 
(MRI) of the abdomen to rule out other disorders. The doctor may do video capsule endoscopy Video Capsule Endoscopy Video capsule endoscopy (wireless video endoscopy) is a procedure in which the person swallows a battery-powered capsule. The capsule contains one or two small cameras, a light, and a transmitter... read more to evaluate the intestines of people who have symptoms that suggest Crohn disease.
Treatment of IBD
Drugs
Sometimes surgery
Diet and stress management
Although there is no cure for IBD, many drugs (see table Drugs That Reduce Bowel Inflammation Caused by Crohn Disease Drugs That Reduce Bowel Inflammation Caused by Crohn Disease 
and table Drugs That Reduce Bowel Inflammation Caused by Ulcerative Colitis Drugs That Reduce Bowel Inflammation Caused by Ulcerative Colitis ), including aminosalicylates, corticosteroids, immunomodulating drugs, biologic agents, and antibiotics, can help reduce inflammation and relieve the symptoms of IBD.
People with very severe disease sometimes need surgery.
Diet and stress management
Most people and their families are interested in diet and stress management. Although some people claim that certain diets have helped improve their IBD, including one with rigid carbohydrate restrictions, diets have not been shown to be effective in clinical trials. Doctors sometimes recommend stress management techniques to help people deal with the stress of having a chronic disease.
Health maintenance
IBD puts people at increased risk of developing certain infections and disorders because of their underlying disease, poor nutrition, or use of immunomodulating drugs. Vaccinations and diagnostic tests and screenings can help lessen the risk.
The influenza vaccine Influenza Vaccine The influenza virus vaccine helps protect against influenza. Two types of influenza virus, type A and type B, regularly cause seasonal epidemics of influenza in the United States. There are... read more is needed every year to help protect against the flu. The pneumococcal vaccine Pneumococcal Vaccine Pneumococcal vaccines help protect against bacterial infections caused by Streptococcus pneumoniae (pneumococci). Pneumococcal infections include ear infections, sinusitis, pneumonia... read more helps protect against bacterial infections caused by Streptococcus pneumoniae. People who are age 50 and older should receive the shingles vaccine Shingles Vaccine There are two herpes zoster (shingles) vaccines. The newer herpes zoster vaccine is preferred over the older herpes zoster vaccine because it provides better and longer-lasting protection. The... read more . Those who are younger than age 50 who have IBD may receive the vaccine after discussing with their doctor whether they should be vaccinated. The shingles vaccine should be given before people start taking immunomodulating drugs when possible. People should also receive routine tetanus-diphtheria Tetanus-Diphtheria Vaccine The tetanus-diphtheria (Td) vaccine protects against toxins produced by the tetanus and diphtheria bacteria, not against the bacteria themselves. There is also a combination vaccine that adds... read more , hepatitis A Hepatitis A Vaccine The hepatitis A vaccine helps protect against hepatitis A. Typically, hepatitis A is less serious than hepatitis B. Hepatitis A often causes no symptoms, although it can cause fever, nausea... read more , hepatitis B Hepatitis B Vaccine The hepatitis B vaccine helps protect against hepatitis B and its complications ( chronic hepatitis, cirrhosis, and liver cancer). Generally, hepatitis B is more serious than hepatitis A and... read more , and human papillomavirus Human Papillomavirus (HPV) Vaccine The human papillomavirus (HPV) vaccine helps protect against infection by the strains of HPV that are most likely to cause the following: Cervical cancer, vaginal cancer, and vulvar cancer in... read more vaccines if appropriate. COVID-19 vaccines COVID-19 Vaccine Coronavirus disease 2019 (COVID-19) vaccines provide protection against COVID-19. COVID-19 is the disease caused by infection with the SARS-CoV-2 virus. There are multiple COVID-19 vaccines... read more that use mRNA, such as those made by Pfizer-BioNTech and Moderna, are recommended for people who have IBD, including those who are taking immunomodulating drugs.
Women who have IBD and who are not taking immunomodulating drugs should have cervical cancer screening with a Papanicolaou (Pap) test Screening for Cervical Cancer Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more 
every 3 years. Women who have IBD and who are taking immunomodulating drugs should have a Pap test every year.
People who have IBD and are taking or plan to take an immunomodulating drug or biologic agent should be screened for skin cancer Screening for skin cancer Skin cancer is the most common type of cancer. Skin cancer is most common among people who work or play sports outside and among sunbathers. Fair-skinned people are particularly susceptible... read more every year and should use sunscreen Sunscreens Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. Overexposure to ultraviolet light causes sunburn. Sunburn causes painful reddened skin and sometimes blisters, fever... read more 
and wear protective clothing Clothing Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. Overexposure to ultraviolet light causes sunburn. Sunburn causes painful reddened skin and sometimes blisters, fever... read more .
People at risk of decreased bone density (osteoporosis) should have a dual-energy x-ray absorptiometry (DXA) scan Bone density testing Osteoporosis is a condition in which a decrease in the density of bones weakens the bones, making breaks (fractures) likely. Aging, estrogen deficiency, low vitamin D or calcium intake, and... read more 
.
More Information
The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
Crohn's and Colitis Foundation of America: General information on Crohn disease and ulcerative colitis, including access to support services
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)—Crohn Disease: General information on Crohn disease, including information about research and clinical trials
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)—Ulcerative Colitis: General information on ulcerative colitis, including information about research and clinical trials
