The Nioxin Density Rescue Serum is an overnight thickening solution that regrows hair and reduces shedding. The $50 formula hails from a brand Alyssa Milano has used and is a fan-favorite at Amazon.

A 47-year-old “can’t believe” how much “thicker” their hair grew back.

I love a product that works overnight. For one, I find it easier to remember to use things I can place on my nightstand (versus digging around among the zillions of products in my medicine cabinet). I particularly love the concept of a hair growth treatment that works while I sleep, like the Density Rescue Serum from Alyssa Milano-used brand, Nioxin. Fans of the $50 formula swear it works in mere weeks and requires minimal effort to incorporate into an existing nighttime routine. 

Nioxin Density Rescue Serum

$50 at Amazon

The Nioxin Density Rescue Serum is a potent hair growth solution that builds up fine hair and strengthens weak strands to stymie shedding. Furthermore, the formula spurs new hair growth, delivering thicker, healthier hair in as little as two months of nightly use. 

Unlike many hair growth formulas—which can be messy, oily, or cumbersome—Nioxin’s solution is a water-light, non-greasy liquid. Its pipette-style dropper makes application to the roots breezy and precise, and it requires no rinsing post-use. Plus, it works on damp or dry hair—making for seamless incorporation into any existing hair-washing routine. Four drops of serum, massaged into the scalp prior to sleep, is all that’s required for optimal results. 

As for its ingredients, caffeine is among the key growth-promoters, stimulating blood flow to the scalp—which, in turn, creates a healthy environment for new hair growth. The serum also contains panthenol, which strengthens fragile strands. Specifically, it adds suppleness to brittle, breakage-prone hair, consequently preventing premature snapping.

Shoppers are impressed by the overnight thickening treatment. A 47-year-old with thinning hair said they “can’t believe [their] results” after two months, citing a visibly “thicker” mane. According to another fan, the formula “really helped” with regrowth. Plus, they noted, it’s “not oily, smells nice, and does not leave any residue.” Finally, another reviewer dubbed Nioxin’s serum a “godsend” in light of how it dramatically reduced shedding. “I was amazed when I wasn’t pulling out clumps of my hair [in the shower],” they said. 

For thicker, fuller, stronger hair, shop the Nioxin Density Rescue Serum at Amazon. And to supercharge your results, consider incorporating additional growth-spurring hair heroes from the brand, below.

Hair Fall Defense Intensive Daily Leave-In Hair Treatment

$50 at Amazon

Density Defend Styling Root Lifting Spray

$21 at Amazon

Nioxin Density Defend Hair Thickening Gel

$21 at Amazon