Does mixing alcoholic drinks really make you more drunk?
There are some very general answers to your question.

Definitely, there is a lot of magical thinking. We as humans are very prone to anecdotical evidence and extrapolations from incomplete data, even more so when we are drunk.
As an interesting &quot;proof&quot; is the fact that the German counterpart of the saying &quot;beer after wine and you'll feel fine, wine after beer will make you feel queer&quot; is &quot;Wein nach Bier, gönn' ich Dir, Bier nach Wein, lass es sein&quot; -- which means the exactly opposite of the English saying (beer after wine is bad, wine after beer is fine).

Many kinds of alcohol contain unwelcome additional substances, for example fusel alcohols. Definitely, &quot;mixing&quot; broadens the range of these additions.

Mixing can lead to a misperception about the actual amount of alcohol that was taken in. Many people who would not drink a vodka and drive have no problem driving after a half a liter of beer (which contains same amount of alcohol two shots of vodka).