Are IBS and Allergies Related?

Is There Such a Thing as Atopic IBS?

young man sneezing into a tissue
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A brand new area of IBS research involves the relationship between allergies and IBS. This focus differs from the attention given to the relationship between food allergies and IBS. Researchers have coined the term "atopic IBS", pulling from the medical term atopic, to describe a possible subgroup of IBS patients who also suffer from common allergies. Research in this area is just barely emerging; the following is an overview of what has been done to date.

What Is Atopic Disease?

Atopic disease refers to conditions in which there is an IgE response to common external stimuli. The IgE response triggers the production of histamines, resulting in allergy symptoms. Common atopic diseases include:

Is There a Link Between Allergies and IBS?

To try to answer that very question, a study was conducted to assess the rate of comorbidity between allergies and IBS. The study was prompted by the fact that mast cells, which are a large part of the allergic response, have been thought to play a part in IBS for some patients. This preliminary study indicated that patients seen in the allergy clinic were significantly more likely to suffer from IBS than those seen in the general medicine clinic. Patients with atopic diseases were three times more likely to meet the diagnostic criteria for IBS than those without atopic disease.

Another study took a deeper look at the question through the use of physiological measures, such as skin prick tests, serum markers and duodenal biopsies.

Study participants were individuals who described themselves as having "food sensitivities", the majority of whom suffered from IBS, while a little more than half had atopic disease. The results indicated that although the physiological measures were all higher in atopic vs. non-atopic patients, there was no difference in terms of GI symptoms between the two groups.

This study thus sheds some light on atopic disease, but offers little in terms of understanding whether or not this is a relationship between allergies and IBS.

What About Treatment?

If researchers were to find a link between allergies and IBS, new treatment options might emerge. One such study has already been conducted, assessing the effectiveness of the medication 'ketotifen' versus placebo on visceral hypersensitivity in IBS patients. Ketotifen is an antihistamine and a mast cell stabilizer that is used to treat asthma and allergic conjunctivitis. Visceral hypersensitivity was measured through the use of balloon insertion in the rectum and rectal biopsies were conducted to assess the presence and action of mast cells. The results were promising, as decreased rectal sensitivity was seen in the individuals who received ketotifen and had previously demonstrated rectal sensitivity. The ketotifen group also experienced a decrease in abdominal pain and improved scores on quality of life measures.

Interestingly, ketotifen had no effect on the release of histamine or tryptase by the mast cells in the lining of the rectum. Obviously, these results must be replicated by further studies before any conclusion can be drawn about the use of ketotifen as a medication for IBS.

Is There Such a Thing as Atopic IBS?

At this point, the term "atopic bowel" is just that -- a term. However, ongoing research into the possible links between allergies and IBS certainly holds the potential for a better understanding as to what causes IBS. If research supports the notion that atopic IBS is a valid description for some IBS sufferers, it certainly opens up exciting new avenues for effective treatments.


Klooker, T., "The mast cell stabiliser ketotifen decreases visceral hypersensitivity and improves intestinal symptoms in patients with irritable bowel syndrome" Gut 2010 59:1213-1221.

Lillestol, K., "Indications of 'atopic bowel' in patients with self-reported food hypersensitivity" Alimentary Pharmacology & Therapeutics 2010 31:1112-1122.

Tobin, M. "Atopic irritable bowel syndrome: a novel subgroup of irritable bowel syndrome with allergic manifestations" Annals of Allergy, Asthma and Immunology 2008 100:49-53.

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