Many people with Interstitial Cystitis (IC) use a product called Prelief.
Prelief is used beneficially in terms of pain and urgency with Interstitial Cystitis and Prostatitis [drugs.com]. These tablets or powder help to reduce the acidity of food and drinks. An IC bladder cannot handle anything too acidic. This product may help you to tolerate something that you miss consuming. I know a lot of people use Prelief to be able to drink a cup of coffee.
Each tablet contains 345 mg calcium glycerophosphate (65 mg of elemental calcium). The tablets also contain 0.25% magnesium stearate as a processing aid. Two tablets are equivalent to 690 mg calcium glycerophosphate (130mg of elemental calcium). Each ¼ teaspoon usage of powder is comparable to two tablets [drugs.com].
Prelief appears to reduce cellular inflammation in the urinary bladder.
Remember to check with your medical professional before starting any supplement or over-the-counter product.