This expression means an unpleasant fact or experience that is difficult or painful to accept. The saying refers to taking medicine in the days when pills were typically large and often bitter. For instance, the bark of the cinchona tree was used to fight malaria, but the quinine in it was extremely bitter. The phrase is in use since the sixteenth century.

Übersetzung:

in den sauren Apfel beißen

Gegenteil(e)

The opposite of "to be a bitter pill to swallow" is "to be a pleasant need".

Synonym(e):

You could also say: to grin and bear it.