How are IBS and IBD different?

Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) can cause similar symptoms, but they are actually very different conditions. IBS is a syndrome, which means that it is diagnosed on the basis of a set of symptoms that a person experiences. It is what is known as a “functional” disorder, which means that the digestive system is not functioning like it should, but it is not due to damage to the digestive system. IBS most commonly affects the colon (the large intestine) and the rectum. Researchers are still not sure exactly what causes IBS, but it is generally thought to involve changes in the way the colon moves and contracts as digested food moves through the digestive tract.1,2

IBD, on the other hand, refers to a set of related conditions that involve inflammation and damage inside of the digestive system. The most common IBD conditions are ulcerative colitis and Crohn’s disease. Ulcerative colitis mainly affects the colon, while Crohn’s disease can affect any part of the digestive system, from the mouth to the anus.

What are the symptoms of IBS and IBD?

IBS and IBD can cause some similar symptoms, such as:1,2

  • diarrhea
  • abdominal pain
  • constipation

However, IBS can cause symptoms that are not as common among people with IBD, such as mucus in the stool, gas, and bloating. People with IBS may feel relief from symptoms after a bowel movement, while this is not usually the case for people with IBD.

IBD can also cause symptoms that cannot be caused by IBS, such as:

  • anemia
  • bloody diarrhea or black stools
  • weight loss
  • fever

What are the key differences between IBS and IBD?

The key difference between IBS and IBD is that IBD causes long-term, chronic inflammation inside the digestive tract. This inflammation can lead to serious and permanent damage to the digestive tract over time, even when it is treated. IBD is generally a more serious condition than IBS. To control their symptoms, people with IBD may need to have treatment with very powerful medicines called corticosteroids or immunosuppressants. Many people with IBD may need to have surgeries or other types of treatments or procedures that require hospitalization. Having IBD can also make a person more likely to develop colon cancer.1,2

IBS has symptoms that can also affect a person’s quality of life in many ways, but mild symptoms can often be controlled by changes in diet, stress reduction techniques, and over the counter medications. Stress is a common trigger for IBS symptoms, so finding ways to manage stress can be very effective in controlling symptoms. People with IBS do not usually require the types of very strong medications that people with IBD may need, and most people with IBS do not require treatment in a hospital. However, people with IBS have a higher chance of developing other types of functional disorders, including:

  • fibromyalgia
  • chronic pelvic pain
  • chronic fatigue syndrome
  • temporomandibular joint (TMJ) disorder

To find out if a person’s symptoms are being caused by IBS or IBD, healthcare providers may need to use diagnostic tests in addition to a physical examination and medical history. Such tests may include blood tests, stool samples, or endoscopy. Endoscopy involves inserting a tiny camera mounted on a flexible tube into the mouth or anus, which allows a healthcare provider to look at the inside of the digestive tract. People with IBD have damage to the digestive tract that is visible with endoscopy, while people with IBS do not have this type of damage.

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