I try to stick to the "Beer before liquor" rule (... for the most part), but new studies show that other than the carbonation factor, the rule may be irrelevant.  The fact that you are mixing alcohol might just be that you are drinking enough (no matter what type) to make you sick in the first place.  For those of us that don't want to take full blame for the bottle flu, what can we point the finger at?  How about these little jerks call congeners. Congeners are produced during fermentation and they are toxic. Lighter colored alcohols contain less congeners than their darker colored brethren. This is probably the reason Godsmack sings about a whiskey hangover as opposed to vodka or gin. Here is the more scientific explanation: