Pentosan polysulfate sodium (Elmiron) is the only oral medicine that is FDA approved for treating the pain and discomfort of IC. In double-blind, placebo controlled clinical trials, 38 percent of patients treated with Elmiron for three months reported improvement of their IC symptoms. In open-label trials, 61 percent of patients reported improvement.

Elmiron is thought to work by restoring a damaged, thin, or “leaky” bladder surface. This surface (glycosaminoglycans, or GAG layer) is composed of a coating of mucus, which protects the bladder wall from bacteria and irritating substances in urine. It is believed that Elmiron functions as a synthetic GAG layer, but the drug’s mechanical action in IC is unknown.