Kate Somerville, a celebrity facialist whose long list of Hollywood clients includes Jessica Alba and Debra Messing, has a beauty secret that many women would prefer to keep secret.

At least once a week, she lathers up with her own brand of face wash and, using a Gillette Mach3, the men’s razor, proceeds to shave her face. Ms. Somerville, who is in her 40s, has sworn by this routine since her 20s.

“I hate to say this, but personally I get hairs above my upper lip, and have forever,” Ms. Somerville said, adding that waxing irritates her sensitive skin. “Initially I did it because of the hair, but then I noticed that it was a great exfoliant and that my makeup went on a lot better.”

Marilyn Monroe and Elizabeth Taylor shaved their faces, according to Ms. Somerville, who said that an aesthetician who worked with them told her. She declined to reveal which of her celebrity clients shave their faces, but said that she recommends it widely and that many comply.