These Hair-Thickening Products Are Seriously Game-Changers

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Every year I make the same birthday wish: To magically wake up with thicker, fuller hair. (Spoiler: It has yet to come true.) Which is why I’ve tested more than 100 of the best hair-thickening products out there in my adult life, from hair-growth vitamins to hair-thickening shampoos to hair-growth oils—all in an effort to make my fine hair look denser and more voluminous. To aid in my quest, I consulted three experts: certified trichologist William Gaunitz, celebrity hairstylist Andrew Fitzsimons, and synthetic biologist and beauty expert Evan Zhao to get to the root of the problem and what I can do to fix it.

There are a ton of products out there that can be used to improve your current flat-hair state, and they all work differently. As Fitzsimmons tells Cosmo, “Products like hair-thickening shampoos work by adding volume to the thinner, flatter strands to temporarily give more lift to the overall appearance of the hair.” Gaunitz further adds that he’s found thickening products to be especially effective when they're using chemical volumizers to blow out the cuticle, which is the protective scale-like layer on the outside of the hair shaft. “When a hair-thickening product opens the cuticle,” he tells Cosmo, “it in turn enhances the overall size and diameter of the hair shaft.” And when shopping for hair-thickening products, Fitzsimmons recommends looking for ingredients such as Keratin, caffeine, collagen, or biotin.

Trust me, I know this feels like a lot of info to digest! That’s why I’ve gone ahead and done the research for you to find the very best products you should add to your lineup, and I promise they won’t disappoint. Take a peek at some of my findings below.

Now keep scrollin' for our complete list of hair-thickening products below, featuring reviews from real-life testers who have all waxed poetic about these gold-star formulas. And if when you make it to the very end, read on for expert insight into how to narrow your search to one product and more.

Perfect Volume Thickening & Conditioning Hair Masque

This hair mask is legit excellent for my fine, flat hair because it makes my hair look more voluminous and moisturizes my ends—all without weighing my hair down. How? It uses rosemary and sunflower extract which helps improve hair health by balancing the scalp and strengthening hair follicles. Plus, it features rice starch which helps build volume.

THE REVIEWS: "I live in a humid area also, so I'm always on the hunt for a product that will give my hair volume and work immediately," writes one tester. "This NatureLab Tokyo Perfect Volume Thickening & Conditioning Hair Mask is it! I use it at night before I have to go into the office, and my hair looks amazing and full of life in the morning! It leaves my hair feeling thicker and more moisturized; in perfect condition for styling it in the morning. I have straight, fine, and damaged hair from years of bleach and color. You can imagine how lifeless and flat my hair is! I love how easy it is to apply and how you can see results immediately. This is my new favorite hair mask and I highly recommend this mask!"

5% Minoxidil Foam for Hair Thinning and Loss

Minoxidil, aka my one-true love, is "a growth stimulant that works by improving blood flow to the hair follicle over time," says Gaunitz, and is the main ingredient in Rogaine and Hers. It’s the only FDA-approved treatment for people with long-term hair loss (like postpartum hair loss, or damage-related hair fall), but it does require continued use to maintain results, and it's not for everyone. Which is why you should def check with your dermatologist first to determine if it’s the right solution for you.

THE REVIEWS: “Wow, this stuff really works,” writes one tester. “I had some thinning all along my hairline, and I’ve been using minoxidil for a year now and my hair is much thicker and I can see a big difference!”

Hair-Building Fibers

If you're looking for a product that helps downplay thinning hair, but also looks ~real~, you need to try this cult-favorite tinted powder. Just shake it throughout your roots, massage it in with your fingers, and the formula’s itty-bitty keratin fibers (the same protein in your hair) will cling to your strands to make them look seriously thick and full until you hop in the shower.

THE REVIEWS: “I am soooo happy with Toppik Hair Building Fibers!” writes one reviewer. “I am very self-conscious about my thinning hair, and I have tried everything. This is the best product for making my hair look thicker.”

Maximista Thickening Spray

This volumizing spray helps to not only protect my hair from heat damage while blow-drying, but to also leave it looking majorly full and amped-up by the end. How? Because of the formula’s PVP, a polymer that coats your strands to make them look thicker, along with watermelon fruit extract, an antioxidant that helps to protect hair from heat.

THE REVIEWS: “I have thin/flat hair and have tried MANY different products that promise volume/body and life!” reads one tester’s review. “They’ve all left my hair greasy, and even flatter than before. But not this stuff! It smells awesome, it gives my hair so much volume and it lasts! Two days later, and it’s still got some life! Love this product!”

Multi-Peptide Serum for Hair Density

This water-based serum is packed with moisturizing peptides and your early morning savior: caffeine. Caffeine, as a reminder, is rich in the type of antioxidants that can help reduce inflammation (a potential reason for stunted hair growth). Before bed, just massage a few drops of the serum throughout your scalp to help repair your moisture barrier, and, hopefully, get thicker, fuller hair over time.

THE REVIEWS: “I have been using this serum every time I wash my hair—one to two times a week—for a little over a month now,” writes one reviewer. “I section my hair to ensure even coverage of the scalp, and I take time to massage it in. I have noticed a HUGE difference in the thickness of my hair at the root, as well as hair loss.”

Mielle Organics Rosemary Mint Scalp & Hair Strengthening Oil

If you have curly hair or 4c hair, you probably already know the magic of this hair oil. But the hype is real, y’all, because it's loaded with sealing oils, like rosemary oil, castor oil, and jojoba oil that coat your hair and scalp to protect against water loss that can lead to dry, irritated scalp.

THE REVIEWS: “This is so good!!” one tester writes. “I've struggled with thin, very fine hair pretty much all of my life and I've searched for something to help even a little bit and this made my hair much thicker, healthier, and longer!! Definitely recommend!”

Niospray Strong-Hold Hairspray

So you loaded up on thickening creams and mousses, but your style still falls flat in a few hours (a story I know all too well). Spritz on this highly rated, strong-hold hairspray to keep your roots lifted without weighing them down or leaving your hair feeling stiff and crunchy. And beyond its major hold, the formula also contains polymers that wrap around each strand to make your hair look a little thicker overall too.

THE REVIEWS: “If you want a spray that doesn't just coat the outside of your hair, but gives it body, shape and adds thickness, BUY THIS PRODUCT!,” writes one reviewer.

Body Volume Boosting Shampoo

As much as I love dry shampoos and root powders for volumizing my hair, I don’t love how they leave my roots gunked up with product. Enter: This caffeine-based shampoo that improves the appearance of fine and thin hair to look bouncier and fuller-bodied. Its formulation also promotes both hair growth and strength.

THE REVIEWS: "I have fine hair but a good amount of it and it gets oily at my roots very quickly," writes one reviewer. "I use mousse, blow drying, and dry shampoo as much as possible to try to combat this. Now that I've started using this shampoo, my hair has never been more manageable. It feels so soft and has some texture while my roots stay lifted for around three days!!!! My hair has never gone this long without needing a wash or five pounds of dry shampoo. Also, the scent is a huge bonus, it smells like a bougie salon."

Fructis Mega-Full Thickening Lotion

A spray...lotion? Yup! This v-affordable formula is ultra light, almost like water, and unlike any type of lotion you’re probably used to. It uses copolymers that coat your cuticles in a film to temporarily thicken your hair, says trichologist Evan Zhao. For best results, spritz it onto your towel-dried hair from the middle to the ends, then style your hair as usual.

THE REVIEWS: “Why has no one told me about this miracle potion?!?!” writes a tester in a review. “My hair is very fine, and it thinned after a major surgery. This product is amazing at giving thickness and volume. I’m now a customer for life.”

Blossom & Bloom Ginseng + Biotin Volumizing Root Powder

A greasy scalp is basically the antithesis to volumized hair. Which is why you should absolutely be dusting this powder through your roots when you want some body. The formula uses four types of starches to soak up oil and coat your individual strands to create the illusion of volume. Just shake the powder onto your dry roots and massage it in with your fingers, or sprinkle it on your hands and scrunch it into your hair for a lil extra body and texture.

THE REVIEWS: “This has become my go-to solution for next-day hair,” one reviewer writes. “I use just a little about an inch from where I normally part my hair and use my fingers to give the roots a nice boost. It works! My fine, thin hair looks full and like I washed it and blow-dried it with a round brush.”

Thick & Full + Biotin & Collagen Volumizing Conditioner

The MVI (Most Valuable Ingredient) in this conditioner? Copolymers that temporarily plump up your hair strands to leave them looking thicker and denser. And unlike some conditioners that are filled with heavy oils, this one uses a mix of peptides and biotin to lightly moisturize without weighing you down.

THE REVIEWS: “I have a lot of hair, but it is very fine and limp, so I tried the OGX Thick and Full conditioner,” writes a tester. “I've noticed a great difference! I don't blow dry, just let it air dry. My hair is thicker and has more body instead of being so limp.”

Thickening Tonic

If you can’t be bothered with a 10-step hair routine, try this hair-thickening spray, which volumizes with corn starch, strengthens with wheat protein, and moisturizes with castor-seed oil. Just spritz it through your towel-dried ends from root to tip, massage it through your hair, and blow-dry or air-dry for a smooth, volumized finish.

THE REVIEWS: “I have thinning, baby fine hair, and every time I use this I get compliments on how pretty and voluminous my hair looks,” one reviewer writes. “This is the only thickening product I've tried over the last 10 years that actually does what it says without weighing my hair down.”

Full Thickening Mousse

I've been burned by mousse in the past that has left my hair feeling crunchy and heavy. But now, several years later, this ultra-light mousse exists, and it's nothing like the stuff from the early aughts. It coats my strands with polymers that help thicken up my hair while locking my hairstyle into place, yet doesn’t feel stiff or crunchy.

THE REVIEWS: “I have the thinnest, flattest hair, and this product makes my hair feel three to four times thicker,” writes one tester. “I have tried so many products over the years, and this has by far given me the best results.”

Flourish Hair & Scalp Herbal Infusion

FYI: Trichologist Isfahan Chambers-Harris developed this hair-thickening treatment for moisturizing and soothing your scalp, which can inadvertently lead to fuller-looking hair and potential growth (remember: an inflamed scalp prob won’t produce denser hair). It uses a host of botanical extracts—like saw palmetto, lavender, and green tea—along with sealing rosemary, pumpkin, and safflower oils to coat your hair and reduce moisture loss.

THE REVIEWS: “A must have,” writes one reviewer. “I have never seen my daughter's 3c-hair respond to products like the ones available in this line. INCREDIBLE!!!”

Hairline Powder

My secret weapon for fuller-looking roots? This cover-up powder. I just dab it onto the sparse areas around my hairline and through my part with a dense makeup brush and blend it in—et voilà, my hair suddenly looks as thick as it did before I started bleaching it in middle school.

THE REVIEWS: According to one tester, “This hairline powder is a miracle. It works so incredibly well and looks natural. You would have to be inches from my scalp and know what to look for to realize that it wasn’t just my own hair. I’m so happy with this product, and I wish that I had found it years ago.”

What products make your hair thicker?

All types of products can make your hair look thicker: shampoo and conditioner, styling products, powders, and topical treatments. But they all work differently, whether they fake the appearance of thickness by dissolving oils or concealing with pigments, or by coating your strands with polymers that temporarily swell up your strands, or by using active ingredients (see: minoxidil) or soothing ingredients to work directly on your scalp for growth.

How can I thicken my thinning hair?

If you're looking to thicken your thinning hair, first visit a board-certified dermatologist. They'll determine why your hair is thinning in the first place and advise on the best approach. This could include a topical plan, like incorporating volumizing polymers, tinted hair powders, or moisturizing ingredients into your hair routine. Or they could decide a hair-growth treatment, like minoxidil or a prescription option, is right for you.

Fitzsimmons tells Cosmo there are many different reasons why someone may be experiencing hair loss. This can include hormonal changes, stress, or simply genetics. Because everyone’s hair journey is so personal, hair-thickening products work in different ways for different people. It takes some trial and error, but not all hope is lost and change is possible!

Do hair thickening products actually work?

Yes, hair-thickening products actually work, though some are temporary while others work to thicken your hair over time. For example: Temporary thickening products use follicle-coating ingredients that make the hair look thicker until you shower. On the other hand, you have clinically backed ingredients like rosemary oil and saw palmetto, shown to stimulate hair growth, plus FDA-approved hair growth treatments like minoxidil for treating pattern hair loss.

How to choose the best hair thickening product:

Visit your doctor

If you’re experiencing hair loss or thinning, make an appointment with your dermatologist to get a proper diagnosis, check up on your hair health, and discuss options like minoxidil or prescription treatments, says Dr. Chambers-Harris.

Consider your hair goals

There are many different types of hair-thickening products, each of which caters to a unique concern. Maybe you're looking to make sparse, thin areas look fuller? Try a fiber filler or colored powder, which will help target specific areas and temporarily fill them in. Or, if you’re experiencing hair loss and thinning, talk to your doctor about a topical solution like minoxidil.

But if you’re not experiencing thinning and just want to make your hair look a bit more voluminous, incorporate a hair-thickening product like a spray or mousse that will coat your hair with copolymers to temporarily plump your hair strands. Or, try a starchy powder to soak up excess oils and give your hair a lift. Similarly, if you’re looking for more volume, swap in a sulfate-filled clarifying shampoo once or twice a month to dissolve oils and buildup, which are basically your worst enemy if you want fluffy, Matilda Djerf-style hair, k?

Meet the experts:

• William Gaunitz is a certified trichologist and founder of Advanced Trichology. He specializes in hair growth and scalp health, with a specific interest in nutritional, hormonal, and inflammatory alopecia.

• Andrew Fitzsimmons is a celebrity hairstylist and brand founder who has worked with A-list talent such as Bella Hadid, Madonna, Mariah Carey, Kim Kardashian, Kylie Jenner, and more.

• Evan Zhao is a synthetic biologist, chemical engineer, and CEO and co-founder of Revela. He’s an expert in utilizing AI to discover targeted molecules for beauty, wellness, and health.

Why trust 'Cosmopolitan'?

Marisa Petrarca is a contributing beauty writer for Cosmopolitan with over five years of experience researching and writing about makeup, skin, and hair, ranging from collagen creams to alpha-hydroxy acids. She discussed hair thickening products with the hair experts featured in this story and dove into reviews and research to recommend the best products.

Daisy Maldonado is the associate shopping editor at Cosmopolitan with four years of experience researching, writing, and editing beauty stories that range from in-depth hairstyling tool reviews to the best hair brushes for fine hair. She regularly tests and analyzes hair products for efficacy while working with the industry’s top hairstylists to assess new formulas and brands.

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