I try a lot of skin-care products, both as part of my job and because I love it. As such, everything from Cetaphil cleanser (which, love) to triple-digit moisturisers have graced my face. However, aside from very rare exceptions, no potion has been more sophisticated than 111Skin's Y Theorem Repair Light Serum. 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 American and European board-certified 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.
In addition to the skin-renewing benefits hinted at above, 111Skin's YTheorem Repair Serum 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 flat 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 £215, it is understandable to baulk at the price point. However, after reading more about what went into this bottle, I was truly 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).
At Refinery29, we’re here to help you navigate this overwhelming world of stuff. All of our market picks are independently selected and curated by us. All product details reflect the price and availability at the time of publication. If you buy or click on something we link to on our site, we may earn a commission.