Irritable Bowel Syndrome vs. Inflammatory Bowel Disease

Written by Michael Kerr and Kristeen Cherney | Published on May 14, 2015
Medically Reviewed by George Krucik, MD, MBA on May 14, 2015

IBS vs. IBD

When it comes to the world of gastrointestinal diseases, you may hear a lot of acronyms such as IBD and IBS. Inflammatory bowel disease (IBD) is a broad term that refers to chronic swelling (inflammation) of the intestines. It’s often confused with the non-inflammatory condition irritable bowel syndrome (IBS). Although the two disorders share similar names and some of the same symptoms, they have distinct differences. Learn the key differences here. Be sure to discuss your concerns with a gastroenterologist.

Prevalence

IBS is extremely common. In fact, the International Foundation for Functional Gastrointestinal Disorders estimates that it affects up to 15 percent of the American population. According to Cedars-Sinai, about 25 percent of Americans complain of IBS symptoms. This is also the most common reason why patients seek out a gastroenterologist.

Most people with IBS will never develop IBD. Still, a person who has been diagnosed with IBD may display IBS-like symptoms. It’s also important to know that you can have both conditions at the same time. Both are considered chronic (ongoing) conditions.

Key Features

IBD comes in the form of:

  • Crohn’s disease
  • ulcerative colitis
  • indeterminate colitis

Unlike IBD, IBS isn’t classified as a true disease. Instead it’s known as a “functional disorder.” This means that the symptoms don’t have an identifiable cause. Other examples of functional disorders include tension headaches and chronic fatigue syndrome (CFS).

Contrary to popular belief, IBS isn’t a psychological condition. IBS has physical symptoms, but there is no known cause. Sometimes the symptoms are called mucous colitis or spastic colitis, but those names are technically incorrect. Colitis is an inflammation of the colon, whereas IBS does not cause inflammation. 

People with IBS show no clinical signs of a disease and often have normal test results. Although both conditions can occur in anyone at any age, it seems to run in families.

Symptoms

IBS is characterized by a combination of:

  • abdominal pain
  • cramps
  • constipation
  • diarrhea

IBD can cause the same symptoms, as well as:

  • eye discomfort
  • extreme fatigue
  • joint pain
  • rectal bleeding

Both can cause urgent bowel movements.

IBS patients may experience a feeling of incomplete evacuation as well. Pain may be experienced across the entire abdomen. It most often manifests in either the lower right or lower left side. Some people will also experience upper right side abdominal pain without any other symptoms. 

IBS differs in the amount of stool produced. IBS can cause loose stools, but the volume will actually fall within the normal limits. (Diarrhea is defined by volume, not necessarily by consistency.)

IBS sufferers with constipation typically have normal colonic transit times — the amount of time it takes for stool to travel from the colon to the rectum — as well. 

Depending upon the main symptom, IBS patients are classified as constipation-predominant, diarrhea-predominant, or pain-predominant. 

Role of Stress

Since the inflammation of IBD is absent in people with IBS, it’s difficult for researchers to understand the precise causes of the latter condition. One notable difference is that IBS is almost always exacerbated by stress. Stress reduction techniques may help. Consider trying:

  • meditation
  • regular exercise
  • talk therapy
  • yoga

IBD may flare up in both low-stress and high-stress situations. 

According to Dr. Fred Saibil, author of the book “Crohn's Disease and Ulcerative Colitis,” many people don't feel they can discuss IBS because of social stigmas. "You don't hear a lot of people talking about their 'tension vomiting' or 'tension diarrhea' or 'tension bellyaches,'" he says, "even though these are every bit as common." 

Dr. Saibil notes also that there’s still some confusion over IBD because doctors once believed that the condition was caused by stress. There’s no evidence that that is the case, however, and IBD patients should in no way feel they brought the condition on themselves.

Treatments

IBS may be treated with certain medications such as intestinal antispasmodics like hyoscyamine (Levsin) or a dicyclomine dicyclo-mine HCL (Bentyl).

Dietary and lifestyle changes seem to help the most. People with IBS should avoid aggravating their condition with fried and fatty foods and caffeinated beverages.

IBD treatment depends on the form diagnosed. The primary goal is treating and preventing inflammation. Over time, this can damage the intestines.

Outlook

IBD and IBS may seem to share similar symptoms, but these are two different conditions with very different treatment requirements. With IBD, the goal is to reduce inflammation that causes symptoms. IBS, on the other hand, may not be treatable with medications because there is not an identifiable cause. A gastroenterologist can help determine your specific condition and offer the best treatment plan and resources to help you manage symptoms. While both IBS and IBD can cause chronic issues, a you can achieve a symptom-free lifestyle with proper management. 

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