My hair has always been fine. Fine in the technical sense—slippery smooth with strands small in diameter and generally quite limp—and fine in the “this will do, I guess” sense. I’ve tried mousses and root sprays and texturizers that have given me a temporary boost, but I assumed that its natural state was probably unchangeable. Then, in 2022, Nécessaire The Scalp Serum landed on my desk.
Like a good beauty editor, I decided to put it to the test, though between the extremely lightweight formula (I’m used to scalp serums feeling more viscous, like skin serums; this one truly just feels like water) and my sporadic-at-best applications (the brand emphasizes consistent daily use for the best results), I did not have high hopes. But then, several months in, my hair started to feel…different. It took two hands to hold it all. My ponytails started to more closely resemble that of the equines they’re named for: thick (for me), shiny, and bouncy. The length, which had previously seemed to tap out just below my collarbones, was reaching mid-boob territory.
The real validation came at the hair salon that following spring after I’d been using the serum for about four months. “Your hair feels thick,” my stylist, Casey Yardley, who I’d been going to for three years, said during the consultation phase of the appointment. “What are you doing?” I shrugged, honestly still not convinced that the serum had done anything. I know hair goes through phases, changing texture and thickness throughout your life. Maybe my mid-thirties was already going to be my luscious hair era, serum or not.
I continued to assume this was all a coincidence until I finished that first sample bottle, which, because of the aforementioned inconsistency, lasted me way longer than its intended 30-day run. A few months later, that newly acquired thickness started to wane. Once the ponytail got back to rattail status, I sent an email to Nécessaire’s PR team requesting a restock, this time with the intention to be vigilant in both application and documentation.
Why it works
On its website, Nécessaire claims that 90 percent of people saw thicker hair and 94 percent saw fuller hair after using the serum (paired with the brand’s shampoo and conditioner) for 90 days. There aren’t many available details about that self-reported study, but dermatologist Michelle Henry, MD, and cosmetic chemist Sherry Backman both tell me that the primary active ingredient, Capixyl, is fairly well established as an effective ingredient for hair thickening. “Some studies have shown it can be just as effective as 3 percent minoxidil,” Dr. Henry says, who notes that, in her experience, Capixyl seems to have a lower risk of causing facial hair and irritation than minoxidil.