Whats the difference between IBS and IBD?
16th January 2018

In some respects, IBS (irritable bowel syndrome) and IBD (inflammatory bowel disease) are easy conditions to confuse. On top of having similar sounding names, the two have many similar symptoms – sufferers may experience abdominal pain, cramps, constipation and diarrhoea as well as feeling generally unwell.

That said, the conditions are quite distinct, with different causes and different treatments. This means if you're experiencing bowel problems, it's important to see a medical professional who can give you a definitive diagnosis.

How they differ

The most important difference between the two is that IBS is classed as a 'functional' disease (meaning the symptoms lack an identifiable cause) whereas IBD involves some damage to the gut that will be obvious on a physical examination.

"With IBS, there are problems with the way in which the diet, gut nervous system and microbiome interact with the brain and central nervous system," says Dr Simon Smale, a consultant gastroenterologist and medical adviser at The IBS Network. "With IBD, people get episodes of inflammation within the gut, leading to changes you can see with an endoscope. So in IBS, the lining of the bowel looks normal, while in IBD there may be patches of abnormality."

Strictly speaking, the name IBD is an umbrella term for several different conditions, including ulcerative colitis and Crohn's disease. Ulcerative colitis affects the inner lining of the colon and rectum, whereas Crohn's disease can affect any part of the digestive tract.

In addition to the digestive symptoms, IBD patients might also experience unexplained weight loss, rectal bleeding, joint pain, anaemia and skin problems. These symptoms vary from person to person and are likely to take a relapsing-remitting course. In other words, you have flare-ups every so often, with periods of good health in between.

Although IBD can significantly impact your day-to-day functioning, it would be wrong to suggest it is always more serious than IBS. As Dr Smale explains, both are chronic conditions, which can range from mild to very severe.

"I think the symptoms of IBS can be as debilitating as the symptoms of IBD, and it can be very difficult for both patients and clinicians to tell the difference," he says. "For that reason it's important that people have tests that help us differentiate between the two."

Diagnosis and treatment

When you go to the doctor with IBS symptoms, they may order a series of blood tests to rule out other conditions. Typically, this will include a full blood count, a test for markers in the blood of inflammation, and a test for coeliac disease (another condition that can cause similar symptoms). You may also be asked to carry out a stool test.

If all these tests come back negative and you're suffering from typical symptoms, that provides a strong indication you are suffering from IBS. You may be prescribed a medication like an intestinal antispasmodic, as well as guidance about lifestyle or dietary changes. As a general rule, self-management is considered a cornerstone of treatment.

Any positive results, however, will be grounds for further investigation. If the doctor suspects IBD, you may be referred for an endoscopic procedure such as a colonoscopy (sometimes involving a biopsy) or a medical imaging procedure like an X-ray.

With IBD, treatment is geared towards reducing the inflammation in your bowel. Medications might include immunosuppressants (which dampen down the immune response in the gut), steroids (used for short-term treatment during a relapse) and a newer class of drug called biologics. Some people may eventually need surgery to remove the damaged part of the gut.

However, as Dr Smale points out, both IBD and IBS present very differently between individuals, meaning treatment will vary considerably from person to person.

"There are some people with Crohn's disease who will need surgery, but there are others who are asymptomatic most of the time without needing any specific treatment," he says. "Equally there are people with IBS who are very disabled by their symptoms, while there are others who can manage it by recognising the triggers."

Whether you're at the milder end of the spectrum, or are suffering badly, self-diagnosis is inadvisable. It's always best to rule out IBD before attempting to self-manage your condition.