Bladder pain syndrome/interstitial cystitis (BPS/IC) is a disabling chronic condition that affects up to 7% of women in the USA. In men, BPS/IC seems to be less common, but might be underestimated because it can be confused with chronic prostatitis. The aetiology and pathophysiology of BPS/IC are not well understood. Consequently, diagnosis and treatment is challenging and most therapies used to date are off-label. These therapies include bladder instillation with dimethyl sulfoxide (DMSO) and BCG, as well as hyperbaric oxygen therapy. Overall, botulinum neurotoxin A injection, intravesical sodium hyaluronate instillation and DMSO instillation seem to be the best-performing treatments, with response rates of 79%, 76% and 75%, respectively, and can be used effectively as second-line or third-line therapies for BPS/IC. However, additional high-quality randomized controlled trials are necessary to improve the available data.