IBS and IBD: Two Very Different Disorders


Many people are confused about two distinct gastrointestinal disorders -- IBD and IBS. Different intestinal disorders can produce similar symptoms. Irritable bowel syndrome (IBS) is a condition that produces some symptoms similar to those of inflammatory bowel disease (IBD), but they are not the same condition, and they involve very different treatments. Therefore, getting an accurate diagnosis is essential to managing your condition properly. The following Q&A will give you an overview of IBS and how it differs from IBD.

Irritable bowel syndrome (IBS) is classified as a functional gastrointestinal disorder, which means there is some type of disturbance in bowel function. It is not a disease, but rather a syndrome, defined as a group of symptoms. These typically include chronic abdominal pain or discomfort and diarrhea, constipation, or alternating bouts of the two. People with IBS are also more likely to have other functional disorders such as fibromyalgia, chronic fatigue syndrome, chronic pelvic pain, and temporomandibular joint (TMJ) disorder.

IBS has been referred to by many names, including mucous colitis and spastic colitis, but these terms are inaccurate and lead to confusion about what IBS is. While the word "colitis" refers to an inflammation of the colon (large intestine), IBS does not cause inflammation. Unlike ulcerative colitis patients, IBS sufferers show no sign of disease or abnormalities when the colon is examined.

IBS does not produce the destructive inflammation found in IBD, so in many respects it is a less serious condition. It doesn't result in permanent harm to the intestines, intestinal bleeding, or the harmful complications often occurring with IBD. People with IBS are not at higher risk for colon cancer, nor are they more likely to develop IBD or other gastrointestinal diseases. IBS seldom requires hospitalization, and treatment does not usually involve surgery or powerful medications, such as steroids or immunosuppressives.

IBS can, however, cause a great deal of discomfort and distress, and can severely affect an individual's quality of life. Its symptoms can range from mildly annoying to disabling -- impinging on a person's self-image, social life, and ability to work or travel. People with IBS are more likely to seek health care for both gastrointestinal and non-gastrointestinal complaints compared to people without IBS. It is estimated that IBS results in direct and indirect medical costs of over $20 billion annually.

Who Gets IBS?

According to the International Foundation for Functional Gastrointestinal Disorders (www.iffgd.org),  IBS affects at least 10% to 20% of adults in the U.S. -- mostly women -- and is second only to the common cold as a cause of absenteeism from work. It is the disorder most commonly diagnosed by gastroenterologists and one of the top ten most frequently diagnosed conditions among U.S. physicians. IBS usually begins in late adolescence or early adult life -- most often at times of emotional stress.

What are the symptoms?

Symptoms can vary widely among individuals, but most IBS sufferers experience some degree of chronic and persistent abdominal pain, constipation, diarrhea, or constipation alternating with diarrhea.

Other symptoms include increased amounts of mucus in the stool, gassiness, abdominal bloating (the sensation of fullness), abdominal distention (swelling), an urge to move the bowels with the inability to do so, and occasionally, nausea. Symptoms commonly occur after eating a large meal or when you are under stress. Often, symptoms are temporarily relieved by having a bowel movement.

Anemia, bleeding, weight loss, or fever -- which may occur in IBD -- are not symptoms of IBS. People with these symptoms should consult a physician immediately.

How is it diagnosed?

Since IBS is a disturbance in function (the way the body works), it can not be confirmed by visual examination or measured with typical diagnostic tools. Therefore, a diagnosis of IBS is based on the presence of symptoms and elimination of other causes. To do this accurately, physicians require a detailed medical history and a thorough physical examination.

Some of the criteria for diagnosing IBS include at least 12 weeks (not necessarily consecutive) in the preceding 12 months, of abdominal discomfort or pain that is accompanied by at least two of the following features:

  1. relief upon defecation, and/or
  2. onset associated with a change in frequency of stool, and/or
  3. onset associated with a change in form of stool.


Once symptoms are confirmed, tools such as blood or stool tests, endoscopy, x-rays, and psychological tests may be used to help rule out other diseases.

What Causes IBS?

The cause of IBS is not fully understood. Because no organic cause has been found, IBS was once thought to be caused by stress. However, researchers now believe that, while stress can aggravate the condition, IBS is caused by a disturbance in the way the brain and the gut interact.

The gastrointestinal tract is controlled by a complex system of sensory and motor nerves that exchange information among the organs, the spinal cord, and the brain. The colon reacts to the information it receives is by contracting or relaxing its muscles, and secreting fluid or mucus. As part of the normal digestive process, food enters the colon from the small intestine, where strong muscle contractions begin moving it to the rectum. The colon absorbs water and nutrients from the food, and what remains passes out of the body as stool. But the muscles of the colon, sphincters, and pelvis have to synchronize their contractions for the stool to be expelled normally.

People with IBS exhibit irregular patterns of colon motility (muscle contraction). The term "irritable" is used because the nerve endings in the lining of the bowel are unusually sensitive, and the nerves that control the muscles of the gut are unusually active. Ordinary stimuli -- eating, stress, hormonal changes, gaseous distension, and certain medicines or foods -- can trigger an exaggerated response in people with IBS, causing spasms. Sometimes the spasm delays the bowel movement, causing the stool to remain in the colon for a long time. Too much water is absorbed, causing it to become hard and difficult to pass, leading to constipation. At other times, spasms push the stool through the colon so rapidly the fluid cannot be absorbed, resulting in diarrhea. Spasms can also create other symptoms of IBS such as cramps, urgency or bloating.

How is it Treated?

Since the underlying mechanisms that cause IBS are not yet understood, treatment typically targets the symptoms. Unfortunately, even this can be difficult, since people have varying symptoms, either alternating or concurrently. The first line of treatment for IBS should be education about the disorder. For mild cases, symptoms can often be managed with dietary changes and stress management techniques. Medications can be an important part of relieving symptoms in more severe cases, but no single medication or combination of medications works for everyone with IBS. Some patients may benefit from seeing a therapist for stress management, relaxation training, or other coping strategies. Other treatments, such as cognitive behavioral therapy, acupuncture, and hypnotherapy have also shown some encouraging results in initial studies. Be sure to discuss with your doctor what treatments are right for you.

Some physicians believe it's possible for certain patients with IBD to also have IBS. Others think it is highly unlikely that the two conditions would coexist, and the topic is highly controversial. For these patients, physicians need to be very careful in managing treatment, so the IBD is not undertreated with antidiarrheals and antispasmodics and the IBS is not overtreated with immunosuppressives.

For more information about IBS, contact IFFGD at 888-964-2001, or visit their "About IBS" Web site.



For further information, call CCFA at our Information Resource Center: 888.MY.GUT.PAIN (888.694.8872).

The Crohn’s & Colitis Foundation of America provides information for educational purposes only. We encourage you to review this educational material with your health care professional. The Foundation does not provide medical or other health care opinions or services. The inclusion of another organization’s resources or referral to another organization does not represent an endorsement of a particular individual, group, company or product.

About this resource


Published: June 1, 2012