Eli5: does mixing alcohols really make you sick? If it does, why?

Question

I’ve always heard things like liquor before beer. You’re in the clear and that mixing brown and white can go bad, but why are you not supposed to mix alcohols?

In: Biology

Answer 1

There is a German saying: Wein auf Bier das rat ich dir. Bier auf Wein, dass lass sein.
Means: I advise you to have wine on beer. Beer on wine, don’t!