@SarahGen-- I haven't, but don't cranberries also contain lots of vitamin C?
So I suppose it's true. You could take vitamin C tablets instead of cranberry pills. It might not treat it, but I'm sure it will help with the symptoms.
One other over-the-counter bladder infection medicine (that's not labeled so) is an effervescent antacid. I'm not exactly sure how it works for a bladder infection, but it reduces my symptoms and makes me feel better. I guess the citric acid and potassium bicarbonate help kill bacteria?