Is it the Cola or the caffeine that causes bladder infections?

I drink soft drinks almost non stop and sometimes I get severe bladder infections with aches, pains and as they say on TV ads, urgency and frequency. A few days of water and/or cranberry juice cures it. I was wondering if it was the cola itself or the caffeine that causes the bladder infection? In other words would drinking excessive iced tea or coffee also cause it and would drinking non-caffeine drinks not cause it?

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