To quote The Sound of Music, these are a few of my favorite things: celebrities spilling their beauty secrets and skincare products that help people look and feel their best (though, an honorable mention goes to my cat's cotton ball belly). So after both Camila Cabello and Alicia Keys mentioned that their routine features products from Osmosis Skincare, my curiosity was piqued — especially because shoppers in their 50s dub its serum a "fountain of youth in a bottle."

I know, high claims. But as Alicia Keys told Voguein 2020, her "favorite thing to use right now is Osmosis," and coming from someone who regularly walks the red carpet without makeup, she knows high-quality skincare (probably why she launched her own line). From her and Cabello's endorsements, the brand's cleansers are top-tier — but if you're looking for even more powerful line-smoothing action, Osmosis's StemFactor Growth Factor Anti-Aging Serum is the move.

"I'm turning 50 next month and I'm regularly mistaken for being in my 30s," wrote one Amazon reviewer of the formula's effect after an esthetician recommended it to them. Another 50-year-old said that after trying "every product known to man," their skin began to look tighter and smoother within days of beginning the serum; other people confirmed the quick turnaround, discussing the "fantastic results in minimal time."

Shop now: $96–$120; us.lookfantastic.com, and amazon.com

The praise builds from there. A fan dubbed the product "as close to a miracle serum" as skincare can be thanks to its effect on fine lines and brown spots, and another wrote that it decreased wrinkles "dramatically, almost before your eyes" (and lessened their dark circles, too). On Dermstore, where the serum is currently sold out, other customers noted it softened their skin's texture.

So, the age-old question: Why are people seeing such satisfying results? The brand's founder and formulator, Dr. Ben Johnson, MD, says the difference comes from the topical growth factors — aka large proteins — in the serum. A patent-pending method of feeding the human stem cells and fibroblasts creates over 600 growth factors, he tells InStyle, and encapsulating them in exosomes allows the growth factors to deeply penetrate into the skin. Per the brand's studies, those factors significantly increase collagen and elastin production.

"As we age, our skin loses 1 percent of its growth factor population each year starting at age 25," Johnson says. "Osmosis Growth Factor Serum contains the highest growth factor variety and strength of any serum in this class, which allows us to replace the lost skin repair activity as we age in a gentle but highly effective way." He's not kidding: As a last Amazon shopper wrote, "Acne scars, age spots, [and] fine lines all improved. After a month, I don't even wear face makeup anymore."

Sounds like great news for skin, and the serum's popularity is a testament to its power. On top of being sold out at Dermstore, just over a dozen of the Osmosis StemFactor Growth Factor Serums are left at Amazon — but there are still bottles available at LookFantastic (and the price is down to $96 at the latter if you want $24 off the typical cost).