Give Methigel Urinary Acidifier with food, since it may cause gastrointestinal upset when fed on an empty stomach. (1800petmeds.com)
Unfortunately, in trying to «fix» a cat's unnatural alkaline urinary pH — caused by human greed in the first place — pet food manufacturers created even more problems by adding urinary acidifiers in the form of dl methionine, etc., which led to the formation of calcium oxalate (CaO) crystals / stones in many cats. (catinfo.org)
It is important to not supplement the cat's diet with urinary acidifiers unless it is actually needed because a too acidic pH can cause a different kind of stone to form (calcium oxalate stones). (veganoutreach.org)