I’ve had many, many UTIs over the years. Eventually, because we were traveling, a Mayo physician put me on Methenamine - also known as Hiprex. My Mayo nephrologist tried to take me off of it last year but the UTIs came back . She must’ve had some concern about its effect on the kidneys because although she put me back on it I am now only taking a half a pill a day. No UTIs for some time.