turn someone's head
Fig. [for flattery or success] to distract someone; to cause someone not to be sensible. Don't let our praise turn your head. You're not perfect! Her successes had turned her head. She was now quite arrogant.
turn someone's head
make someone conceited.turn someone's head, to
To influence someone’s mind-set, particularly so as to make him or her conceited. Seneca had the idea (and his translator the phrase) almost two thousand years ago (Ad Lucilium): “His head was turned by too great success.”