Can you have IBS and IBD?

Answer: Maybe. As many as 40% to 60% of people with inflammatory bowel disease (IBD) have symptoms of irritable bowel syndrome (IBS).¹ But is it really overlapping IBS and IBD? Could it be that hard-to-detect inflammation related to IBD is causing the symptoms? Has there been a misdiagnosis? Does having IBD make a person prone to IBS? Could there be a third condition that explains these symptoms?

It is unsatisfying to have so many unanswered questions, especially about a condition that affects so many people. More research in this area is urgently needed.

What is the difference between IBS and IBD?
IBS is a functional bowel disorder.² This means that the digestive system is not working normally, but no structural cause can be found.³ There are no blood tests to prove that you have IBS. Nothing unusual will show up on imaging tests, and the digestive tract looks normal during a colonoscopy.² The diagnosis is made based on the type and frequency of symptoms.

In contrast, IBD is an inflammatory disease of the digestive tract. Long-term inflammation can cause structural changes to the intestine that can be seen with colonoscopy. The inflammation can lead to serious complications such as fistulas, abscess, and strictures. Blood and stool tests will show that there is inflammation in the body.

The treatments for IBS and IBD are very different. IBS is treated by avoiding triggers, taking medications such as laxatives, anti-diarrheals, antispasmodics, and antidepressants, and managing stress. Surgery is not part of the treatment for IBS. IBD is treated with medications that reduce inflammation and change the way the immune system work. Surgery is often needed to treat IBD or its complications. The medications used to treat IBD are not effective for treating IBS.

What are the symptoms of IBS and IBD?
Both disorders can cause pain, diarrhea, and constipation. However, not all symptoms overlap. Gassiness and nausea are common in people with IBS, while rectal bleeding and fever are symptoms of IBD.

A person with active IBD would be expected to have pain and diarrhea, so these symptoms would not be considered an indication of IBS. However, many people with IBD have symptoms when they are in remission. This fact has caused people to wonder whether the two conditions overlap.¹

Why do some people in remission from IBD have IBS-like symptoms?
One theory is the person is not actually in remission from IBD. Existing tests and tools are not perfect and may overestimate remission. Providers have recently started testing for a protein called “calprotectin” in the stool.¹ If calprotectin levels are above normal, it may be a sign that there is still bowel inflammation. This might explain why some people keep having symptoms, even when their disease seems to be under control.

Nevertheless, there are people with normal calprotectin levels (ie, actually in remission from IBD) that still have IBS-like symptoms. There is a lot of speculation, but not a lot of good evidence to explain this.¹ One thought is that some people have certain traits that make them susceptible to both conditions. Another thought is that the IBD “turns on” or “revs up” certain aspects of the gut-brain axis, causing increased sensitivity and abnormal brain responses to bowel signals.¹ This hypothetical condition might actually be a whole new disorder that is neither IBD nor IBS. Much more research is needed to understand this connection.

Does IBS lead to IBD?
No.^1,2It is quite possible that people diagnosed with IBS first and IBD later were misdiagnosed initially.¹

IBS is not a mild form of IBD. As one expert writes, “inflammation in IBS never even approximates the extent of the inflammatory state that characterizes IBD.”¹ If inflammation plays a role in IBS, it is not well understood. Although some people have proposed that IBS and IBD are two ends of one disease spectrum,⁴ this view is not widely held.¹

How are IBS-symptoms treated in a person with IBD?
There is no clear course of action for people with IBD and IBS-like symptoms.¹ Your gastroenterologist is the best person to talk to about treatment for your particular situation.

One approach is to test for calprotectin in the stool. If you still have low levels of inflammation, treatment with anti-inflammatory medications may help. If the inflammation is gone—or the results are unclear—your gastroenterologist may decide to treat your symptoms as if they were IBS.