But, now researchers in Sweden claim to have discovered a new way of confirming the disorder -- by using stool samples.
In fact, the researchers from the Sahlgrenska Academy at the University of Gothenburg say they have actually identified specific proteins that can be used to identify patients with irritable bowel syndrome (IBS).
"The proteins we've been investigating, granins, are found in various forms with different functions in the nervous, immune and digestive systems.
"Our studies show that IBS patients have higher levels of some granins and lower levels of others in their faeces," lead researcher Lena Ohman said in a release.
The study, which compared 82 IBS patients with 29 healthy subjects, has been published in the latest edition of the 'American Journal of Gastroenterology'.
However, further studies are needed, but if granins can be used to diagnose IBS, it is hoped that this will contribute to the development of new treatments, say the researchers.
Granins (chromogranin A) have previously been shown to serve as biomarkers for other inflammatory diseases in the gut, such as ulcerous colitis and Crohn's disease. The present study looked at the variants secretogranin II and chromogranin B and found that IBS patients have high levels of the former and low levels of the latter.
IBS affects an estimated 10 to 20 per cent of the population and causes chronic or recurring problems with pain and/or discomfort in the abdomen, together with changes in bowel habits. There is currently no cure for IBS, but in many cases the symptoms can be alleviated.