Can having a uti for four weeks cause damage to the bladder?

Probably not: Should not affect the bladder muscle, so that future function should not be impaired unless u r a diabetic. Unless u develop cystitis cystica, consisting of numerous tiny inflammatory cysts (like microscopic pimples) of bladder wall which would make you prone to recurrent utis until it clears up. Or rare possible cause of interstitial cystitis.