Katy Perry

The 38-year-old pop star has been open about her struggles with acne for many years and even starred in the 2010 Proactiv commercial, crediting the treatment with controlling her adult acne.

Speaking about her issues to Refinery29, she said: "I used to have really, really bad skin in my early 20s when things were starting to pop off, so it was stress-related and my body was changing from coming out of the teenage years.”

The singer now also credits a change in her diet in helping to keep her acne under control.