One of the country’s most popular lifestyle drugs turns 15 on Wednesday.

And if that doesn’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 they’re using too much of it.

We’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 — smoothing out countless wrinkles, crow’s feet and other age-related skin divots Botox, along with Prozac and Viagra, is among three lifestyle drugs — a prescription troika most associated with improving the quality of life rather than curing its diseases — and is, quite literally, changing the face of celebrity America.

“People used to think they had to live with what they wore born with,” says Marian Salzman, a futurist and social media expert who serves as CEO of Havas PR. “Then orthodontics came along and introduced a new mindset.”

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 — more than the $1.2 billion in sales for Viagra — Pfizer’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.