10 Best Hair Growth Serums We Tested, Approved by Dermatologists

Glamour testers ranging from 26 to 40, evaluated hair growth serums by looking at the following criteria over a series of weeks to months.

• What we like: It leaves hair feeling stronger and more resilient
• What could be improved: Added fragrance may irritate especially sensitive scalps
• Key Ingredients: Turmeric, caffeine, red clover, mung bean blend
• Dosage: Apply one full dropper to scalp daily
• Size: 1 oz.
• Cruelty-Free: Yes

Glamour contributor Brigitt Earley put this one to the test and has a few tips. “This scalp serum is very runny, so you have to be careful during application—I’ve definitely had it trickle down my face a time or two. But I love that you use it with dry hair, so you can be more consistent. It doesn’t leave strands at all oily, so don’t worry about your fresh blowout. Instead, it sinks right into the scalp for a really refreshing and hydrating effect that people with a dry scalp like mine will find nice and soothing—especially if you’re prone to itchiness.”

Editor tip: Pair this serum with Vegamour’s hair mask for a frizz-free, elasticity-boosting hair routine.

• What we like: Offers additional heat protection and aesthetic improvements to the hair
• What could be improved: Oil formula isn’t ideal for all scalp types, particularly oily scalps
• Key Ingredients: K18 peptide, hemisqualane, squalane, avocado oil
• Dosage: Apply to damp or dry hair as preferred, starting with one to three drops
• Size: 1 oz.
• Cruelty-Free: Yes

“I’ve noticed my strands are much softer and less prone to breakage after using this K18 hair oil for about two month consistently,” says Glamour senior commerce editor Jenifer Calle, who styles her hair for work almost every other day. “My hair is going through a lot of heat-styling, but it’s actually the healthiest it’s ever been, and I’ve noticed a healthy inch of growth in a little over a month.”

• What we like: Reasonable price makes it far more accessible than other options
• What could be improved: Can feel slightly sticky
• Key Ingredients: Redensyl, procapil, baicapil
• Dosage: Apply a few drops to clean scalp daily
• Size: 2 oz.
• Cruelty-Free: Yes

“As someone with a very flat hair type myself, I was excited to give this peptide serum a whirl to see if it added bounce and thickness,” says Glamour commerce writer Alanna Martine Kilkeary. “The good news: My hair actually did look thicker post-application, so much so that I put on a headband to keep it from falling toward my face. This serum also did wonders for my typically knotty hair during the winter and hydrated my roots even after just one application and blow-dry. I’ll definitely continue to use this one throughout the colder months to keep my hair looking resilient, strong, and velvety.”

• What we like: Ideal for hair growth around hairline and edges
• What could improve: Might take time (two months) to see noticeable improvement
• Key Ingredients: Biotin, ginger extract, fermented rice powder, Biopeptide-5, rose extract, bioactive keratin ferment
• Dosage: Apply one full dropper to scalp daily
• Size: 1.7 oz.
• Cruelty-Free: N/A

“I’ve been using the Cécred Restoring Hair Drops every day for about three weeks,” she says. “I apply about half a dropper to each side of my hairline and massage it into my scalp. Typically, I use my fingers to massage, but alternatively, I use the Divi Scalp Scrubber for an extra scrub. It’s really easy to use—not only because of the dropper applicator, but I also appreciate the neutral smell. The drops claim to show results in 16 weeks, but already, I’ve received comments that my hairline looks thicker and darker, which I attribute to Biopeptide-5 (a proprietary blend of five-growth-factor peptides known to visibly improve hair density). I will flag that the product is water-based, not an oil serum, so when applying, make sure to massage it in quickly,” says Glamour editorial assistant Monique Wilson.

• What we like: Thickens and strengthens fine, weaker strands
• What could be improved: We’d love a cruelty-free option
• Key Ingredients: Ceramides, green tea extract, SP94
• Dosage: Apply 2 pipettes for fine hair or 4 pipettes for normal to thick hair, 3 times a week
• Size: 2.2 oz.
• Cruelty-Free: No

“Now that I’m styling my hair more often, I’m noticing some hair breakage at the top of my hair where I tend to pull it the most. This serum keeps that area hydrated and adds some shine to my strands. I’ve also noticed that my hair normally gets greasy after a day, but when I started using this Kérastase hair serum, my scalp stayed fresh for longer,” says Glamour’s Calle.

• What we like: Visibly combats hair thinning; makes hair appear fuller; clinically tested on ages 18 to 59
• What could be improved: Texture is slightly sticky but dries down fast with no residue
• Key Ingredients: Apple stem cells, H2-Grow Complex, bamboo-and-pea-sprout blend, hyaluronic acid
• Dosage: 2 to 3 pipettes
• Size: 2.2 oz.
• Cruelty-Free: No

“I first heard about this pressed stem cell serum when it launched a few years ago, and I’ll be honest, it kind of seemed a little too good to be true,” shares Glamour Kilkeary. “It has a lot of lofty claims, so I was apprehensive about how well it could actually work.” Those claims include clinical trials with 90% of participants showing increased hair growth in six weeks, 100% expressing increased hair thickness, and 100% expressing stronger, healthier hair. Luckily, Kilkeary’s expectations did not fall short. “I tried it for the first time about two years ago when I was experiencing hair thinning around the crown of my head, and applied it at night every day for a few months,” she says. “After that trial, I instantly saw hair growing in the applied area, and now I can’t go a night without it. It’s made such a huge difference in my hair health, and the application is easy to incorporate into any hair care routine, too, which experts say is very important.”

• What we like: Lightweight; non-sticky; helps strengthen baby hairs
• What could be improved: Bottle is leaky
• Key Ingredients: Peptides, caffeine, tea tree oil, amino acids, hyaluronic acid
• Dosage: 2 pipettes a day, morning and night
• Size: 1 oz
• Cruelty-Free: Yes

“Although there’s a lot of it, my hair is quite fine. This means that I’m always hesitant to try products that might weigh it down or make it look greasy. I was really impressed with this water-based serum because it was lightweight and left my hair feeling hydrated and non-oily. Its featherweight texture is one of the best scalp treatments I’ve used for styling too, and I like to use it when I slick back my hair for extra frizz control and hair fall prevention,” says Glamour’s Kilkeary.

• What we like: This thick oil serum helps stimulate hair growth and volumize thin, flat strands
• What could be improved: Expensive
• Key Ingredients: Rootbiomic ferment, peptides, turmeric
• Dosage: 1 pipette a day
• Size: 1 oz.
• Cruelty-Free: Yes

“This serum is ultra moisturizing and gives my hair a ton of body and volume without weighing it down,” says Glamour’s Kilkeary. “I found the oil wasn’t greasy upon application and instead melted effortlessly onto the scalp, mid-shaft, or roots, acting like a scalp serum–hair oil hybrid. I was definitely left with thicker-hair around my ears and by my bangs after consistent use.”

• What we like: Lightweight; improves fullness on fine hair
• What could be improved: Watery texture takes several minutes to dry down
• Key Ingredients: Ashwagandha Exosomes, Irish moss peptides, pea sprout extract
• Dosage: One full dropper
• Size: 1 oz.
• Cruelty-Free: No

“I really love the Nutrafol drops, but I did find that they take a second to dry, which is funny because they feel like the exact consistency of water. That said, once dry, they don’t leave behind any residue or semblance of oiliness. I applied about three quarters of a dropper to spots at my temples, particularly on my part and the very back top of my head, and then rubbed it in. Since they take a second to dry, I found that the best time to apply them was at night right before bed,” says Glamour contributor Brittany Loggins.

• What we like: Evidence-based claims; effective
• What could be improved: Packaging is fairly lackluster
• Key Ingredients: Minoxidil 5%
• Dosage: Half a capful once daily
• Size: 2.11 oz.
• Cruelty-Free: No

Karen Chang, a senior finance director at Condé Nast who has been dealing with hair thinning for years, is one of our testers. She says it feels like hairspray, so just be aware that it can leave your hair feeling a little sticky. She’s only been testing for a month, so we’ll follow up with her full review in our next refresh.

When looking for hair growth serums, it’s important to look for products containing ingredients that have scientific evidence in promoting hair growth. “Minoxidil is FDA-approved to promote hair growth by increasing blood flow to the scalp, and essential oils like rosemary and peppermint oil have been shown in clinical studies to stimulate hair growth comparable to low-concentration minoxidil,” Dr. Song says.

Meanwhile, Dr. Yadav suggests looking for ingredients that support the growth of healthy hair by fostering a healthy environment for the hair follicles, such as Aminexil, caffeine, and ceramides.

She also points to rosemary oil, clover extract, and saw palmetto extract, which help block DHT, a hormone connected to hair loss—though she notes the evidence here isn’t as robust as others. Dr. LoGerfo recommends ingredients that increase hair density and volume like biotin, amino acids, omega-3 fatty acids, niacinamide, peptides, keratin, and hyaluronic acid.

Remember that it takes time and commitment to determine if any product is working, especially a hair growth product. Because the rate at which hair grows is around half an inch per month, it can be difficult to measure the effectiveness of a hair growth topical in fewer than three months. If you’re consistent, you should start to see new growth around that time period—according to Dr. Yadav, you should see hairs sprouting up along the hairline or at the top of the scalp. Depending on the type of hair serum, by three months you can also expect decreased shedding, lengthening of once-shorter baby hairs, and stronger, shinier hair strands.

While many of the serums on this list can be applied to dry hair, you should aim to apply them while your hair is damp. “This allows the serum to penetrate the hair shaft and the scalp a bit more effectively, which always helps maximize any results,” says Kerry E. Yates, a trichologist and founder of Colour Collective.

Hair growth serums can be used everyday, according to Rachel Nazarian, MD, a board-certified at Schweiger Dermatology based in New York City. “Some ingredients can be decreased to three times weekly use for maintenance,” she notes. It’s always best to speak with your board certified dermatologist to learn about the specifics of your hair regimen.

Some scalp and hair care ingredients to look out for when addressing hair growth include:

• Rosemary Oil: “It’s been shown to increase blood flow, and nutrients to hair follicles, which is the primary pathway thought to be responsible for hair growth,” says Dr. Nazarian. She also adds that the ingredient is anti-inflammatory, which can treat different forms of irritation and damage.
• Minoxidil: This clinically proven ingredient helps with hair growth and is available over the counter. “The important thing to remember here is that you need to give these ingredients at least six months to work their magic, and that you need to continue indefinitely to maintain results,” says Dr. Nazarian.
• Biotin: If you’re dealing with vitamin deficiencies that are leading to hair loss, biotin is a great ingredient to improve hair thickness and aid nail health, according to Dr. Nazarian.

• Geeta Yadav, MD, a board-certified dermatologist and founder of Facet Dermatology
• Teresa Song, MD, a board-certified dermatologist
• Jodi LoGerfo, MD, a doctor of nursing practice and family nurse practitioner certified in family medicine and dermatology
• Kerry E. Yates, a trichologist and founder of Colour Collective
• Rogerio Cavalcante, owner and stylist of The Second Floor Salon
• Rachel Nazarian, MD, a board-certified at Schweiger Dermatology based in New York City
• Pooja Rambhia, MD, a board-certified dermatologist at Union Derm
• Dendy Engelman, MD, a board-certified dermatologist in NYC