"expert in cosmetics," 1925, American English, in state ordinances regulating the profession, from cosmetology + -ist. The earlier word was cosmetician (1914).
The manufacturers of cosmetics have a new friend in the shape of a New Yorker, who calls himself a complexionist and prescribes a mixture of sulphur and glycerine to be rubbed on the face every night and washed off in the morning with ammonia. An elephant might not suffer from this treatment, but a human being who attempts it may reckon on about a year of repentance for every week of rubbing. The regular physicians might do a worse thing than expose the shameful ignorance of this "complexionist." ["Ladies' Home Journal," August 1888]