Why This Celeb-Favourite $376 Serum Is Seriously Worth The Splurge

I try a lot of skincare products, both as part of my job and because I love it. As such, everything from Cetaphil cleanser (which, love) to triple-digit skincare brands have graced my face. However, aside from very rare exceptions, no potion has been more sophisticated than 111SKIN's Y Theorem Repair Light Serum NAC Y². If you're not familiar with 111SKIN, allow me to introduce you to the British luxury brand that counts Lady Gaga, Jennifer Aniston, Cate Blanchett and Victoria Beckham among its famous fans: Founded by plastic and reconstructive surgeon Yannis Alexandrides, MD FACS, 111SKIN (Dr. Alexandrides' London practice is at 111 Harley Street), originally developed a topical balm for his patients to aid in post-surgical scar healing. As beauty lore goes, Dr. Alexandrides' bespoke formula quickly became a hit with his patients, who remarked that, in addition to its healing properties, they noticed brighter, firmer skin to boot.

Dr. Alexandrides adapted his exclusive formula into what is now known as 111Skin's Y Theorem Repair Serum NAC Y² — which brings me back to the very expensive bottle seen above. (I opted for the light version of the brand's hero product, which is recommended for oily folks like me.)

In addition to the skin-renewing benefits hinted at above, 111SKIN's Y Theorem Repair Light Serum NAC Y² also delivers round-the-clock hydration and helps protect skin from environmental aggressors (i.e. sun and poor air quality). In other words, it's also great for high-maintenance, twenty-something skin like mine.

For how potent the serum is, I was surprised at just how light the texture was; as you can see in the swatch above, one pump of the serum is crystal-clear and feels only slightly thicker than water. As such, it absorbs almost instantly into my skin but left me looking radiant and balanced. When used in the AM, it didn't leave me feeling greasy all day; at night, I swore I woke up the next morning with my skin not desperately screaming for moisture. (The air in my apartment is on the drier side.) At 28, I luckily don't have noticeable wrinkles or fine lines (oily skin FTW), but I also want to keep it that way, since I'd prefer to explore Botox and fillers later in life, if at all. After nearly three weeks of testing, I can't say that it gave me a brand-new face; however, my skin overall felt really good — as if I'd recently woken from a ten-hour slumber.

At $376, it is understandable to balk at the price point. However, after reading more about what went into this bottle, I was truthfully impressed. The Y Theorem Repair Serum (and its light counterpart) are powered by a trademarked ingredient called NAC Y², which was created by 111SKIN in collaboration with European biochemical engineers. (Fun fact: Earlier iterations of the ingredient were tested on astronauts, as space is one of the harshest environments for skin.) In addition to being the superstar serum's hero ingredient, the NAC Y² complex can be found in all of 111SKIN's Reparative collection products.

Serums are easily the most expensive step of my otherwise simple routine (my rule: splurge on good ingredients that will be on your skin for an extended period of time, unlike cleansers, for example) and 111SKIN's formula took things to a whole new level. Whether you're looking to treat your skin to an elixir of youth or want to maintain a healthy complexion, you won't do better than this overachiever beauty potion. (She's clearly a Virgo — I would know, because I'm one too.)