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Irritable bowel syndrome (IBS) health centre

Irritable bowel syndrome - How do doctors diagnose irritable bowel syndrome?

BMJ Group Medical Reference

There isn't a test that can tell your doctor whether you have irritable bowel syndrome (IBS). It's not a disease that will show up on a scan.

Your doctor will decide if you have IBS by asking you questions about your symptoms and ruling out other illnesses.[37]

Your symptoms

Your doctor will ask you about your symptoms and any health problems you've had in the past. If you've had any of the following symptoms for at least six months, you may have IBS:[37]

  • Changes in your bowel habit (for example, you get diarrhoea or constipation)

  • Pain or discomfort in your abdomen

  • A bloated feeling.

For your doctor to diagnose IBS, one of the following must also be true:[37]

  • You have pain or discomfort that goes away when you go to the toilet

  • You have pain or discomfort that is accompanied by a change in how often you have bowel movements or in how your stools look (they might be harder or softer).

And two of the following must be true:[37]

  • You've had a change in how you pass stools. For example, you may need to go to the toilet urgently or strain to pass stools, or feel as if you haven't completely emptied your bowels

  • You have bloating, tension, or hardness in your abdomen

  • Your symptoms feel worse after you eat

  • You pass mucus from your rectum. Mucus is a thick fluid made in several parts of your body, including your bowels.

Your doctor may also ask whether you get pain in just one spot in your abdomen or if it moves around. In IBS, the pain doesn't usually stay in the same place.

You might also have other symptoms, such as backaches, nausea, feeling tired, having to pass urine frequently or urgently, and occasionally leaking stool. Not everyone has these symptoms, but they can help confirm the diagnosis of IBS.


Your doctor will probably order some blood tests. These are to rule out other, more serious diseases. These tests check for:[37]

  • Anaemia. Anaemia means you don't have enough oxygen-carrying red blood cells. This can happen if you've been bleeding because of another condition in your bowels, such as small growths (polyps) or cancer.

  • Signs of more serious problems in your bowels. These include inflammatory bowel disease and coeliac disease. To read more, see Other problems in the bowels.

Blood tests are probably the only tests you'll need, unless your doctor suspects you might have another illness. If so, you'll probably be referred to a specialist. To read more about other tests, see Further tests to rule out other illnesses.

When you need to go to a specialist

People with IBS often have tests or operations that turn out not to be necessary. Some get referrals to specialist doctors for illnesses that have nothing to do with their bowels.[20] This may be because it can be difficult for doctors to be sure about a diagnosis of IBS.[7]

To help doctors avoid sending people for unnecessary tests, there is guidance about when to send people to a specialist. The guidance says that your GP should refer you if you:[37]

  • Lose weight for no reason

  • Have bleeding from your rectum or blood in your stools (although most people with these symptoms only have piles, also called haemorrhoids)

  • Have a family history of ovarian cancer or bowel cancer

  • Are over age 60 and have had looser or more frequent stools for more than six weeks

  • Have anaemia. This can make you feel tired all the time. It can happen if you've been bleeding because of another condition of the bowels, such as small growths (polyps) or cancer

  • Have a lump in your abdomen or your rectum

  • Have signs that your bowels may be inflamed. This suggests that your symptoms might be caused by inflammatory bowel disease.

Last Updated: March 13, 2013
This information does not replace medical advice.  If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.
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