bitter pill vs encouragement

bitter pill

noun
  • Used other than figuratively or idiomatically: see bitter, pill. 

encouragement

noun
  • Words or actions that increase someone's confidence 

  • Something that incites, supports, promotes, protects or advances; incentive 

  • The feeling of being encouraged 

  • The act of encouraging 

How often have the words bitter pill and encouragement occurred in a corpus of books? (source: Google Ngram Viewer )