Patients and doctors treating interstitial cystitis (IC), a severely painful bladder condition affecting as many as 8 million women and 1.5 million men in the United States, have long noticed a correlation between allergies and IC. Research into this phenomenon by urologist Dr John Hubbard and allergist Dr Steven Smith appears in ICA Update, the quarterly magazine of the Interstitial Cystitis Association.

Steven Smith found that 35–40% of the IC patients he sees have bona fide allergies to foods (of which they were totally unaware) and that their IC gets better when they remove those foods from their diet.

Stimulants, such as coffee and tea, and the acid and spicy foods that have long been known to cause problems for IC patients as they may be bladder irritants even without allergy. But some IC patients also have allergic reactions to some of these foods. Positive skin prick tests for cayenne (a hot pepper) seem to be common.

The effect on IC of treating environmental allergies with shots or medications is less obvious but still seems to be beneficial. About half to a third of the IC patients Steven Smith sees have proven environmental allergies or symptoms, such as hay fever, asthma, recurrent ear infections or chronic urticaria (hives).

Hubbard and Smith are collaborating on a more formal study to find a marker that will help urologists decide which patients may benefit from allergy testing and treatment. Like many urologists, Hubbard uses cystoscopy and hydrodistention under anaesthesia as part of his workup to exclude other conditions that may cause IC-like symptoms. But he is reviving an older practice of taking a biopsy specimen during the procedure and sending it to a pathologist to look for mast cells because, when mast cells reach a certain density, patients seem to benefit from allergy testing and treatment. Mast cells elsewhere in the body are key players in allergic reactions, but their role in the bladder tissue of IC patients has not been clear.

Meanwhile, they continue to assess IC patients for allergy. Not everyone responds but for the high percentage who do improve with allergy management, make the assessment well worth the effort.

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First published in September 2009

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