8 Best Hair-Growth Serums for Fuller, Thicker-Looking Hair

Frequently Asked Questions

What serum is best for hair growth?

It’s okay to expect a lot from your hair-growth serum, especially when you’re shopping for the best hair growth serum. “A good hair-growth serum should reduce hair shedding, increase hair diameter, increase the growth phase of hair, decrease scalp inflammation, and be gentle on the scalp,” Dr. Amin says. “The ingredients I look for are rosemary oil, amla oil, caffeine, green tea, and coconut oil, to name a few. These ingredients have been shown to improve hair strength, promote growth, and undo damage.”

Dr. Lolis adds that many common conditions behind hair loss—including androgenic alopecia and telogen effluvium—are triggered by the hormone dihydrotestosterone (DHT), which can bind to hair follicles and cause them to shrink. “With androgenic alopecia, we typically prescribe medications that block DHT, an enzyme that causes hair loss. However, there are many natural DHT blockers to look out for, such as saw palmetto and zinc,” she says. (You can find zinc in The Ordinary’s Multi-Peptide serum.) Otherwise, Dr. Lolis suggests: “Look for active ingredients like biotin and caffeine, which improve hair strength and stimulate growth.”

Do hair-growth serums work?

“Many hair-growth serums include non-medicated ingredients,” Dr. Amin says. (Translation: You don’t need a prescription for most of them.) “The efficacy of the serums is difficult to ascertain because there are not many randomized controlled clinical trials.”

However, anecdotally, Dr. Lolis has seen evidence that the serums work—especially when they’re used as intended. “Ingredients like biotin and caffeine support the scalp’s environment, helping nourish hair follicles, which can result in denser, stronger hair [over time],” she says. In short, the how-tos on the packaging are required reading, and you should try to adhere to the recommended guidelines if you want to feel blessed in the hair follicles department.

How long does it take to see growth?

“Most users report seeing visible improvements, such as reduced shedding and new hair growth, after about three months of consistent use,” Dr. Lolis says. Dr. Mian agrees, adding that patience is key here. “Hair-growth serums can take a while to show their efficacy,” she says. “I would use a serum for at least three months before deciding if it’s working or not.”

Do essential oils work for hair growth?

Essential oils might help with hair growth, but they can be hit or miss, according to Omer Ibrahim, MD, a board-certified dermatologist based in Chicago. While it’s not yet fully understood how these oils work to promote hair growth, theories abound. “One theory is that these essential oils help increase blood flow to the scalp, and that promotes hair growth,” he says. “Another is that by simply improving the health of the scalp by providing essential fatty acids to the hair follicles, essential oils help hair grow out healthier to give the appearance of thicker hair and also create a fertile ground for hair growth.” He also posits that oils that are inherently anti-inflammatory may support the scalp’s natural microbiome.

That said, not all essential oils are created equal. Below, Dr. Ibrahim breaks down the benefits (and drawbacks) of commonly used oils.

• Rosemary oil shows promise: “Rosemary oil has been shown to help with hair growth, with results similar to that of 2% minoxidil,” he says.
• Castor oil is a no-go: “Castor oil, another popular oil touted for hair growth, doesn’t have strong evidence of stimulating hair growth in clinical settings,” Dr. Ibrahim says. “However, it helps with hair luster and conditioning, which helps prevent hair breakage due to dryness or brittleness.”
• Ginseng extract might work: “Ginseng extract—not an essential oil per se, but found in a lot of scalp oils geared for thinning hair—has good studies showing that it helps both prevent hair loss and promote hair growth,” he says.
• Peppermint oil isn’t one-size-fits-all: Peppermint oil is a buzzy hair-growth ingredient—and while some research and experts point to its ability to boost circulation, it’s not a universal win for every scalp. Dr. Ibrahim notes that oils that create a strong cooling or tingling sensation can be irritating for some people. “That can actually irritate the scalp, which contributes to hair thinning over time,” he says. In other words, it’s less about avoiding peppermint oil entirely and more about paying attention to how your scalp responds, especially if you’re prone to sensitivity.

Meet the experts

• Omer Ibrahim, MD, a board-certified dermatologist and founder of Salmalita Cosmetics, based in Chicago
• Viktoryia Kazlouskaya, a board-certified dermatologist based in New York City
• Hannah Kopelman, MD, a board-certified dermatologist at Kopelman Hair Restoration, based in New York City
• Margarita Lolis, MD, a board-certified dermatologist and Mohs surgeon based in New Jersey
• Papri Sarkar, a board-certified dermatologist based in Brookline, Massachusetts
• Brooke Sikora, a board-certified dermatologist at SkinCare Physicians based in Chestnut Hill, Boston
• Dara Spearman, a board-certified dermatologist at Radiant Dermatology Associates based in Fort Wayne, Indiana

How we test and review products

We always enlist a range of testers for our makeup vertical, but hair-care products and tools are another story. While there are certainly products that can be used across different hair textures, lengths, curl patterns, thicknesses, colors (natural and unnatural), and needs, hair products are often created with specific consumers in mind. Many are created in order to address a concern (dandruff, breakage, brittleness) or to work most effectively for a specific hair type (4C curls, wavy hair, gray hair). You wouldn’t want to pick up a purple shampoo that’s only been reviewed by someone with, say, auburn hair, or a diffuser that’s never been tested by anyone with curls—right?

For our review of the best hair-growth serums, we enlisted the help of multiple editors, writers, contributors, and dermatologists to find the most hydrating, strand-softening formulas out there. Testers considered performance across four primary categories: efficacy, texture and experience, fragrance, and packaging. For more on what’s involved in our reporting, check out our complete reviews process and methodology page.

Our staff and testers

A beauty product is a personal purchase. You might be searching for a face cream to address persistent dryness or a new nail product to add to your Sunday self-care routine; you may simply be browsing around for the latest launches to hit the hair market. No matter what you seek or your individual needs and concerns, Allure wants to ensure that you love anything we recommend in our stories. We believe that having a diverse team of writers and editors—in addition to the wide range of outside testers and industry experts we regularly call upon—is essential to reaching that goal.

After all, can we really say a skin-care product is the “best” for people over 50 if the only testers we’ve solicited opinions from folks who have yet to hit 30? Can we honestly deem a high-end diffuser worthy of your hard-earned cash if it’s never been tested on curls? We’re proud that our staff spans a wide range of ages, skin tones, hair textures, genders, and backgrounds, which means that we are able to fairly assess any beauty product that comes into the beauty closet.