What's the difference between IBS and IBD?

How IBS and IBD differ

The main difference between the two is that IBS is classed as a 'functional' disease - where the symptoms lack an identifiable cause. IBD involves some damage to the gut that will be more clear after examination and further investigations done by a specialist.

Dr Simon Smale, gastroenterologist, explains that with IBS, there are issues with the way in which your diet, gut nervous system, and microbiome interact with your brain and central nervous system.

"People with IBD get episodes of inflammation within the gut, leading to changes you can see using an endoscope," he says. "So with IBS, the lining of the bowel looks normal, while with IBD there may be patches which are not right."

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

These symptoms vary from person to person and are likely to be on and off - so you may have flare-ups every so often, with periods of good health in between.

Although IBD can significantly affect your day-to-day functioning, it is not always more serious than IBS. Smale explains that both are long-term (chronic) conditions, which can range from mild to very severe.

"The symptoms of IBS can be as debilitating as the symptoms of IBD, and it can be very difficult for us to tell the difference," he adds. "So, it's important that people have tests that help 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 blood test to check for markers of inflammation, and a test for coeliac disease - another condition that can cause similar symptoms. You may also be asked to carry out a poo (stool) test.

If all these tests do not find anything and you're having typical symptoms, that provides a strong indication you have IBS. You may be prescribed a medicine such as an intestinal antispasmodic, as well as guidance about lifestyle or dietary changes. Generally, self-management is the most effective treatment.

A positive result to a test which has found an issue may require further investigation. If the doctor thinks you may have IBD, you may be referred for an endoscopic procedure such as a colonoscopy - which may involve a biopsy where they test a small piece of your skin. Your doctor may also refer you to a specialist at the hospital for further investigations.

With IBD, treatment is geared towards reducing the inflammation in your bowel. Medicines might include immunosuppressants, which ease the immune response in your gut, steroids - used for short-term treatment during a relapse - and biologic medicines. Some people may eventually need surgery to remove the damaged part of the bowel. People with IBS are unlikely to need surgery or immunosuppressants.