How Does Hair Thickening Shampoo Work?

A hair thickening shampoo works to make your strands appear denser and more full. Unfortunately, it cannot permanently increase the diameter of individual strands or cause your scalp to grow more follicles.

Siena Gagliano is a beauty editor at Good Housekeeping with 10 years of experience researching, writing and editing skin, hair and nail stories. She relies on experts, including dermatologists and cosmetic chemists, to decode ingredient lists and evaluate formulas.

1. Biotin

While volumizing shampoos and thickening shampoos might sound similar on the bottle, they actually work in different ways. Volumizing shampoos rely on ingredients that create the illusion of fullness by lifting your hair at the roots, whereas thickening formulas use nourishing ingredients that actually make your strands fuller over time.

A hair thickening shampoo that contains biotin is a great option for anyone who wants to encourage healthy scalp and strand growth. The water-soluble B vitamin has gained popularity as a beauty supplement for its ability to strengthen your nails and help you grow longer, thicker hair. But, hair thickening shampoo in your shower, it isn’t as effective as taking a biotin pill. That’s because hair follicles live underneath your skin, and shampoo only gets to the surface of the scalp.

The best shampoos for thickening hair contain ingredients like biotin, bamboo, and keratin, which are all found in nature and proven to nourish and hydrate your locks, and reduce strand breakage. You’ll also find a slew of other botanical ingredients that promote scalp health, like rosemary oil, red clover extract, and saw palmetto.

Biotin is a key ingredient in this shampoo, which racked up 20,700+ five-star reviews on Amazon thanks to its nourishing and soothing scalp formula (think aloe vera, lactobacillus ferment, and more). Then there’s the thickening blend of Amia Indian Gooseberry, niacin, and rice amino acids, which actually help your strands get a little more plump by filling in the cracks in each strand of hair.

2. Keratin

Keratin is the structural protein that makes up your hair, nails, and skin. It also exists in your internal organs and glands. It is less prone to tearing and scratching than other types of proteins you have in your body, which can make it an excellent ingredient in a variety of beauty products.

Hair thickening shampoos use keratin to help each individual strand of your hair appear fuller and thicker. The keratin in these products can also act as a protective shield that helps prevent further miniaturisation of the hair follicles. This, in turn, creates a better environment for healthy hair growth.

Most keratin treatments contain a wide array of ingredients that are meant to boost your natural volume. Some of these products also contain formaldehyde, which is a chemical that can be toxic when used over long periods of time.

Choosing a keratin-enhanced product without formaldehyde is an important step to healthy hair. Look for a non-sticky formula that features a mix of nourishing ingredients like biotin, lavender oil, and keratin. It’s formulated to strengthen, shine without a sticky feeling, and encourage healthy hair growth with BONDING TREATMENT every use. Using a keratin shampoo with this formula can give you the appearance of more voluminous hair with a lustrous shine.

3. Hydrolyzed Collagen

Collagen is the most abundant protein in your body, and it can help set back the clock on wrinkles, strengthen skin and nails, and boost hair thickness and volume. This sulfate-free shampoo is packed with this all-star ingredient, plus other hair-healthy ingredients like bamboo extract (rich in natural silica) and red algae extract. The result: a gentle, effective cleanse that doesn’t weigh down fine strands.

Another sulfate-free shampoo on our list, this volumizing formula is gentle enough to use daily and doesn’t leave your hair feeling dry or crunchy. It’s also infused with glycerin, a super-hydrating ingredient that can make your hair feel soft and shiny. Plus, it contains a blend of plant-based extracts to keep your scalp healthy (like neem leaf and oat kernel), as well as a patented active technology that helps boost root and shaft strength.

When shopping for a thickening shampoo, look for one with ingredients that promise to lift or volumize your hair—and skip anything that promises to be extra moisturizing, as these tend to have too many heavy oils and can cause a greasy finish. Also, consider avoiding products that contain sulfates (surfactants that can strip your hair of its natural oils) or silicones (which can build up on the scalp and weigh it down).

4. Silk Protein

Silk protein is a vegan ingredient that adds a soft, smooth feel to lotions, soaps and hair products. It’s also a beauty-boosting ingredient, often found in shampoos that promote thicker locks. Hydrolyzed silk protein works in a similar way to keratin, helping to strengthen and moisturize your strands.

Most volumizing or thickening shampoos use polymers or light hydrators that temporarily cling to your individual hair strands and make them look slightly swelled until you wash them out. They also contain some kind of nourishing ingredients, such as vitamins or plant extracts, to improve the overall health of your scalp and strands. Some formulas also have dandruff-fighting, strengthening or oil-absorbing properties that help to balance your scalp’s pH and remove excess oils that weigh down fine or limp strands.

The best thickening shampoos also have the added benefit of boosting your natural keratin, so that you can rebuild your own strands to keep them strong and healthy. This shampoo uses a unique mix of plant extracts and proteins to target issues like dullness, split ends and flyaways. It’s especially effective at targeting dandruff, killing it with MVP-level antifungal pyrithione zinc while simultaneously cleaning away dirt and product buildup for fuller, healthier tresses.

This sulfate-free shampoo is a cult favorite for its ability to boost volume while also nourishing fine, limp strands with rich hydrator. It contains bamboo, which is the world’s richest source of natural silica, to help fill in thin strands while also promoting stronger, more resilient strands that won’t break under pressure. It’s also infused with sericin and fibroin, which have skincare benefits (think: hydration and wound healing) and are known to stimulate the production of new keratin.