Ever wonder why coffee makes you pee so much more? You likely know caffeine is a diuretic, meaning, something that causes your kidneys to produce more urine. We were wondering if all this extra pee processing was tough on the ol' bladder, however, research has shown that coffee's diuretic effects aren't that much stronger than, say, a glass of water. So unless you're mainlining five cups a day, or you have bladder issues, your lovely ol' excretory system should be able to handle your coffee needs so you can stay perky.