In bladder instillation, the prescription medication dimethyl sulfoxide, or DMSO, (Rimso-50) is placed into your bladder through a thin, flexible tube (catheter) inserted through the urethra.

CNN: Interstitial cystitis

It's derived from dimethyl sulfoxide (DMSO), which was promoted as a pain reliever in the 1960s and 1970s until scientists discovered in animal tests that it caused eye damage in high doses.

FORBES: Blue Streak