One of the countryโ€™s most popular lifestyle drugs turns 15 on Wednesday.

And if that doesnโ€™t put a smile on the face of any of the thousands of celebrities, and the growing number of millennials who use it, well, it could mean theyโ€™re using too much of it.

Weโ€™re talking Botox, the drug from Allergan that has rung up sales of roughly $21.1 billion since it came on the market in 2002 โ€” smoothing out countless wrinkles, crowโ€™s feet and other age-related skin divots Botox, along with Prozac and Viagra, is among three lifestyle drugs โ€” a prescription troika most associated with improving the quality of life rather than curing its diseases โ€” and is, quite literally, changing the face of celebrity America.

โ€œPeople used to think they had to live with what they wore born with,โ€ says Marian Salzman, a futurist and social media expert who serves as CEO of Havas PR. โ€œThen orthodontics came along and introduced a new mindset.โ€

Kelly Ripa, Simon Cowell, Jenny McCarthy and Courtney Cox are just four of the many celebrities who have copped to using Botox.

While Botox rung up $2.8 billion in global revenue last year โ€” more than the $1.2 billion in sales for Viagra โ€” Pfizerโ€™s 19-year-old erectile dysfunction drug outsold the wrinkle-eraser over its first 15 years $27.1 billion to $21.1 billion, according to industry estimates.