Reviewers call this bottle of hair-building fibers "a best kept secret" for making hair appear instantly thicker while also concealing bald spots and grays. The fibers, which are made of a keratin protein, work by clinging to existing hair strands for a seamless look and a performance that's resistant to rain, wind or sweat. It's available in nine hair colors.

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Promising Amazon reviews: "Amazing best kept secret! Most folks have never heard of these hair fibers but they really work! When I pull my hair back into a pony tail, the baby hair along the front of my face is thin and a few gray hairs popping in. All you see is my scalp and looks bad so I ordered these hair fibers and with a little sprinkle, you can not see the obvious part that looks like a bald spot!
My husband uses the gray fiber because he has some thinning on the top of his scalp. The hair fibers makes his hair look so much fuller and can't see through to his scalp! We both do not use it on a daily basis. Just when we know we will be taking pictures and/or social events. No gimmicks here...works like a charm! A little sprinkle goes a long way! Highly recommend!" — Penny T.

"My hair has thinned around my temples and this product was recommended to me by my hair stylist. I love it! It allows me to wear my hair up it a pony tail without looking thin around the hairline. It’s also great for when my gray roots start coming in and I have a couple days until my next hair appointment. Life saver!" — Jackie Gringle

This gentle purifying shampoo claims to visibly thicken and strengthen hair from root to tip using, while also eliminating buildup on the scalp. Hyaluronic acid hydrates and thickens, while ceramides aid in promoting strand elasticity and a gluco-peptide reduces future breakage and hair is strong enough to grow.

Promising Sephora review: ""Definitely stuck on this one now! This makes my hair look and feel thicker and it makes it feel soft too. There’s no gross smell or feel when you use it and I think it’s worth the price." — kilianm

This popular hair spray is marketed as a solution to temporarily cover grays in between dye jobs, but reviewers also claim that it can help make hair appear thicker by concealing areas where hair is thinner and the scalp is more noticeable. The lightweight formula claims to be water- and smudge-resistant, residue-free and quick-drying. It comes in up to 11 shades that wash out easily on your next shampoo.

Promising Amazon review: "I'm a senior with thinning hair and this spray works great. Just be sure to hold it only 4" approx from your scalp and spray for2-3 seconds and move to a new spot on your head where your scalp is showing thru or your roots are showing. Don't hold too far away from your scalp and don't hold it in one spot. It will feel cold, but that stops almost as soon as you are done spraying that spot. It dries in min. It also thickens your hair so your hair will look fuller. Your fingers may get a little spray on them, but it washes right off with a bit of soap. Also this does wash out if you don't like it. It washes out easily." — Jan S-dell

This isn't the first notable product from Color Wow, the hair care brand known for the viral Dream Coat anti-humidity spray. The Xtra Large Bombshell Volumizer is a weightless pre-styling foam that's made from a proprietary polymer and bamboo that thickens tresses and adds a flexible body. The non-drying formula also doubles as a heat-protectant and promises to leave a glossy and bouncy finish that's free from any sticky residue.

Promising Amazon reviews: "I have tried many products for thin hair but this is the first one that actually worked. My hair looks so much better and thicker and it even looks almost cute when I wake up in the morning because it's going everywhere and looking thick. That is a first I am now a regular customer" — Theresa Bailey

Aveda's thickening tonic claims to expand hair strands from root to tip using an organic wheat-based and botanical formula. Just apply the product on towel-dried hair prior to styling for a result that can add visual fullness to tresses in just one use.

Promising Nordstrom review: "I was skeptical and had to think about it a couple of weeks before I ordered. As I age my hair is really thinning to the point you can see my scalp. I have used the Aveda Thickening Tonic daily for a week and I can notice a difference when I use a blow dryer and lightly dry it then shake the bottle well and apply it. I tried applying it to damp, towel dried hair but didn’t get as good results as when I lightly dried it. I will purchase again, so that is a great recommendation from me!" — MeMe4AnJ

I've used a few products from the Kevin Murphy Plumping line (I adore the shampoo and conditioner duo) and I've always been impressed with how much body and fullness it adds to my hair and how closely my blowouts resemble that of a salon once I'm finished styling. Another winning item that I can recall loving is this leave-in hair plumping treatment, which is a dual-purpose formula that not only can add a thicker appearance to hair temporarily, but contains an oleanolic acid that can help to fortify and strengthen the hair to help preserve the integrity of the hair that you already have. Just apply it evenly to towel-dried hair before styling.

Promising Amazon reviews: "My hair is very fine and thin. Body Mass really does what it says. It plumps up the hair so you look like you have more, and it adds so much body. It's pricey, but to me, it's well worth it." — C Wisniewski

"I have the world's thinnest, wispiest, flattest hair. Truly, I have tried nearly every volumizing, densifying, lifting product. I was actually shocked when this delivered as well as it did. I was resigned to using a different product for the remainder of my days. The other product worked ok, but nothing great. This Kevin Murphy Body Mass Plumping Treatment was bought *at the same time* as the other go-to, as a bit of a hail mary. WOW. It gave my hair healthy volume with zero stickiness, zero tackiness, zero greasiness. It is absolutely the best product I've ever used. I've learned over the years that different products work for different people. But if you're tired of adding yet another volumizing product to your 'product graveyard' then give this a try. I've found my new volume-holy grail." — Amber Seyler

This volumizing and texture powder can add a bit of grip and thickness to fine and thinning hair as well as make it easier to achieve up-dos or conceal areas on the scalp that are particularly sparse. Just sprinkle a conservative amount of the transparent and talc-free powder to roots in order to create an instant lift and hold that lasts.

Promising Amazon reviews: "This hair volumizer is the best! I used to use another brand but the manufacturer discontinued it. I was really upset because I have some hair loss from a past serious illness. My hair stylist recommended the Big Sexy Hair version so I tried it. It works even better than the one I used to use. Makes my hair thicker & fuller!" — BobKat

"I like this powder. I have very thin hair, and this makes it feel so much thicker!" — Dee

Another hair-enhancer that uses fibers to create the illusion of thickness and greater scalp coverage is this powder from Boldify, which features "fibers designed with follicle-mimicking molecules for the most natural blend," according to the brand. Available in 13 shades, the fibers claim to stay put until your next shampoo, even if you sweat or get caught in the rain. For extra security, the brand says you can set the fibers with your favorite hairspray or leave as is post application.

Promising Amazon review: "I have very thin hair and I have always used tinted dry shampoo or root cover up to hide my scalp. I decided I wanted to give this a try and let me tell you it is an absolute must for people with thin hair. I use it every day now to help hide my scalp and in turn my hair looks thicker and it blends in so well that it’s not even noticeable. As an added bonus it is very affordable and way cheaper than how much I was spending on other products. I will say that if you brush it after placing it then it can create streaks so make sure to style then place and pat. But 10/10 recommend for thin hair!" — Diane Miller

According to senior shopping writer and beauty aficionado Lourdes Avila Uribe, she's used the Sachajuan thickening shampoo before and definitely found that it left her hair feeling thicker and fuller, without compromising on smoothness. "It has heat and UV protectants and the brand's proprietary thickening technology that can help to create volume and bounciness. It's a great under-the-radar option for people with naturally thin hair," Uribe previously wrote.

Promising Amazon review: " "When I ordered this thickening shampoo, I didn’t have high expectations. I’m happy to say I was wrong!! My hair used to look limp, thin and lifeless an hour after blowing it dry. With this shampoo, my hair seriously looks twice as thick. It may seem pricey, but you don’t need to use a lot for good results. Therefore it lasts a long time. I’m definitely a customer for life!" — Cheryl Champion

This 4.4 out of 5-star thickening spray from R+Co's Dallas line may help those with fine and thinning tresses finally achieve the big Texas hair of their dreams. This pre-styler is packed with good ingredients like an amino acid complex to offer heat protection, conditioning extracts and pro-vitamin B5 which helps add volume at the roots, but sleek control at the ends.

Promising Amazon review: "R+Co. Dallas thickening spray really works to beef up thin, fine hair. It is easy to apply onto damp hair, and dries to a nice volume of hair where it was very sparse. I really like this product! It works where others have failed, and gives me lush looking, full hair. I have gone completely beige grey, and this product is transforming." — Nicolette Smith

Many reviewers liken this texture spray by Living Proof to a dry shampoo that can not only add a flexible fullness to roots, but also refresh unwashed hair and absorb excess oil thanks to the inclusion of microporous minerals and starch in the formula. It uses resins and texturizing molecules to increase the space in between hair fibers and create a buildable and long-lasting hold.

Promising Amazon reviews: "I love this product, it’s a bit expensive, but the end result is worth it. I’m in my late 70s, have thinning short hair. This product gives more texture and a fuller look." — Cynthia Troxel

"My hair is fine and thin, so after years of using hairspray weighing it down I discovered this product. My stylist mentioned it as a hairspray alternative and to work around the roots similar to dry shampoo. There has been a noticeable change; so much so that a few friends have commented on how much volume my hair has. The smell isn’t off putting or chemical smelling like some products I’ve tried so that’s a plus. It is pricier than the drug store hairspray but definitely worth it in my opinion." — meagan