When it all comes down to it, beer may contain over 95% water, yet it is still a diuretic. Due to the fact that beer contains alcohol, it will always be a diuretic. When you drink beer, you should avoid drinking too much and never, ever, drink beer instead of water. Beer can dehydrate your body fairly quickly, which is one of the biggest cons to drinking beer. Although beer does have several health benefits, they can easily be hindered by drinking too much. To stay on the safe side and avoid headaches and other health effects of beer, you should always drink responsibly, never drink too much - and always drink a few glasses of water when you are drinking beer.