dandruff vs flake off

dandruff

verb
  • To fall or cover with white flakes, like dandruff. 

noun
  • scaly white dead skin flakes from the human scalp; Pityriasis capitis 

flake off

verb
  • To (cause to) come off in flakes. 

How often have the words dandruff and flake off occurred in a corpus of books? (source: Google Ngram Viewer )