fall sick vs sicken

fall sick

verb
  • To become ill; to fall ill. 

sicken

verb
  • To become ill. 

  • To fill with disgust or abhorrence. 

  • To lower the standing of. 

  • To make ill. 

  • To be filled with disgust or abhorrence. 

  • To become disgusting or tedious. 

  • To become weak; to decay; to languish. 

How often have the words fall sick and sicken occurred in a corpus of books? (source: Google Ngram Viewer )