It is important to point out that IBS can never be self-diagnosed, because apart from anything else there are many other conditions which can produce bowel symptoms. These include:

•bowel cancer



•intestinal parasites

•inflammatory bowel diseases (IBDs) such as Crohn’s disease and ulcerative colitis

•celiac disease.

Therefore, make sure that you are diagnosed as having IBS by a medical professional. This is both because something like bowel cancer needs prompt treatment, but also because some of the diseases in the above list can be diagnosed relatively easily and then treated. For example, if the doctors suspect that you have celiac disease they can do a simple blood test which will confirm the diagnosis, and you can then cut out gluten from your diet to prevent the symptoms from recurring.

Diagnosis of IBS itself is unfortunately not as simple as having a blood test. In fact there really is no test for IBS, as it is often more a diagnosis of exclusion. What this means is that a doctor may try to rule out things like celiac disease and inflammatory bowel diseases if they suspect that your symptoms do not fit the IBS pattern.

If the doctor can find no evidence of one of these conditions you may then be given a diagnosis of IBS. Alternatively, some doctors will diagnose you with IBS without any tests if they have the experience to do so, or if your symptoms seem to be typical of IBS.

To help doctors in their diagnosis, something called the Rome criteria was developed. This consists of a list of common IBS symptoms, and also so-called ‘red flag’ symptoms which are not indicative of IBS and suggest that you may have another medical condition which needs investigating.

The Rome criteria are revised every so often, and we’re now on version three. This is what the Rome III criteria say:

The Rome III Criteria

To be diagnosed with IBS, a patient must experience symptoms of recurrent abdominal pain or discomfort and a marked change in bowel habit for at least six months, with symptoms experienced on at least three days of at least three months. Two or more of the following must apply:

1. Pain is relieved by a bowel movement

2. Onset of pain is related to a change in frequency of stool

3. Onset of pain is related to a change in the appearance of stool.

I’m also going to include the earlier, Rome II criteria on this page as they are a lot more detailed than Rome III and might be useful.

The Rome II Criteria

Irritable bowel syndrome can be diagnosed based on at least 12 weeks (which need not be consecutive) in the preceding 12 months, of abdominal discomfort or pain that has two out of three of these features:

1. Relieved with defecation; and/or

2. Onset associated with a change in frequency of stool; and/or

3. Onset associated with a change in form (appearance) of stool.


Symptoms that cumulatively support the diagnosis of IBS:

1. Abnormal stool frequency (may be defined as greater than three bowel movements per day and less than three bowel movements per week)

2. Abnormal stool form (lumpy/hard or loose/watery stool)

3. Abnormal stool passage (straining, urgency, or feeling of incomplete evacuation)

4. Passage of mucus

5. Bloating or feeling of abdominal distension.


Supportive symptoms of IBS:

1. Fewer than three bowel movements a week

2. More than three bowel movements a day

3. Hard or lumpy stools

4. loose (mushy) or watery stools

5. Straining during a bowel movement

6. Urgency (having to rush to have a bowel movement)

7. Feeling of incomplete bowel movement

8. Passing mucus (white material) during a bowel movement

9. Abdominal fullness, bloating, or swelling.

Red flag symptoms which are NOT typical of IBS:

•pain that often awakens/interferes with sleep

•diarrhea that often awakens/interferes with sleep

•blood in your stool (visible or occult)

•weight loss


•abnormal physical examination.


The Rome criteria are not meant to be used by patients to diagnose their own IBS, but can provide a rough guide to indicate whether a patient truly has IBS or not.