Causes

The exact cause of interstitial cystitis isn't known, but it's likely that many factors contribute. For instance, people with interstitial cystitis may also have a defect in the protective lining (epithelium) of the bladder. A leak in the epithelium may allow toxic substances in urine to irritate your bladder wall.

Other possible but unproven contributing factors include an autoimmune reaction, heredity, infection or allergy.