9 Best Hair Growth Serums to Halt Thinning and Add Length

Like that for your scalp, a hair growth serum is a formula that, generally speaking, offers a high concentration of ingredients, such as vitamins, botanical extracts, and essential oils, with the purpose of improving the appearance, strength, and thickness of hair, according to Dr. Shaver. You can also find hair growth serums that contain active ingredients that have been FDA-approved to promote hair growth, like minoxidil.

Depending on their formulation and how often you use them, “hair growth serums can provide a variety of benefits, from improving the healthy appearance of hair to enhancing hair growth,” says Dr. Shaver, who notes that it’s critical to choose a formula that targets your unique hair goals.

First, consider your hair needs. For instance, if your hair tends to be dry, then “look for serums that contain oils to help hydrate the dry hair shaft,” says Dr. Shaver. Meanwhile, if you simply want better, faster hair growth, then she recommends looking for products with ingredients that have been clinically proven to do just that—and have scientific data that support their use. With that in mind, consider these active ingredients, which are mainstays in hair-growth products:

• Minoxidil: One such ingredient that both Dr. Shaver and Dr. Mirmirani recommend is minoxidil, “which is a drug with a long and proven track record for hair growth,” says Dr. Mirmirani. “These minoxidil serums will have a benefit, but are often more costly than over-the-counter minoxidil solution or foam.”
• Rosemary oil: Rosemary oil may “fortify hair by improving moisture and strength [while] delivering nutrients and antioxidants, which protect hair follicle cells from oxidative stress,” dermatologist Dr. Brendan Camp previously shared with Vogue.
• Caffeine: Products with caffeine “may encourage hair growth by improving blood flow and circulation around the root of the follicle,” said Dr. Camp.

Other ingredients may have the potential to spur hair growth, among them peptides, keratin, castor oil, and amla extract. However, “only minoxidil has scientific evidence showing that it can provide benefit in hair growth for women with androgenetic alopecia, or genetic thinning,” Dr. Shaver says. “While many positive case reports exist for various other topical ingredients, the data do not support their use as effective treatment options.”

Finally, consider avoiding formulations that contain additives that might be irritating to the scalp and inadvertently cause dryness or itchiness, such as harsh chemicals, dyes, and fragrances. Instead, Shaver advises to seek out those that have been dermatologist-tested.

For one, supplements, which are often taken orally, can “address specific nutritional deficiencies that may be lacking in a person’s diet,” says Dr. Mirmirani. So, they can be helpful to address systemic causes of hair thinning, such as a deficiency in certain nutrients. (For instance, research has found that deficiencies in iron, vitamin D, and folate may correlate to hair thinning or slow hair growth.)

But these do take longer to work, as supplements “must first be metabolized by the body and dispersed by the bloodstream to be beneficial,” says Dr. Shaver. And oral supplements may have more systemic side effects and interactions with other medications, so it’s especially important to check with your doctor before taking a supplement.

Meanwhile, “the goal of a serum is to target the hair follicle directly by delivering compounds that may allow for improved or optimal hair growth,” says Dr. Mirmirani. These ingredients are those that aren’t typically found in the diet, such as minoxidil and plant-based compounds.

Topical serums tend to be better for “addressing superficial concerns, such as scaling of the scalp and dryness of the hair shaft, since the product can be applied directly to the location that needs the serum,” says Dr. Shaver, who notes that they can also offer benefits more quickly, such as hydrating and comforting the scalp.

The most important step is to test your serum before using it for the first time. “Apply the serum to a small spot on the scalp for a few days to ensure that there is no irritation before applying it more broadly,” says Dr. Mirmirani. “A measured approach is best.” To that end, get comfortable with the fact that you’ll need to be both consistent and patient in your usage, as the results can take time.

As for the application itself, apply a hair growth serum to a clean scalp (though this might vary with the exact product). Ideally, it helps to do it while hair is lightly damp, since this “can help to disperse the product across the scalp and make the scalp more porous and enhance absorption,” says Dr. Shaver. (However, she notes, a very wet scalp would dilute your serum and potentially make it less effective.)

For those with thick hair, then “partition the hair so that the scalp can be exposed and the serum can reach the skin if the purpose is for hair growth, since the product needs to be directly on the scalp so it can be absorbed and reach the base of the hair follicles,” says Dr. Shaver. While many products do provide applicator nozzles that reach through the hair, some droppers aren’t as precise.

Finally, if you’re applying hair growth serum in the evening, consider your skin type—since certain ingredients, such as oils, can potentially rub off onto your pillow and be transferred to skin. “For sensitive or acne-prone skin, either frequent pillowcase changes or wearing a hair bonnet after serum application may be helpful,” she says.

As with any product, consistency is critical to seeing (and maintaining) long-term results. For that reason, Dr. Mirimani recommends daily use for minoxidil. However, “as with any new product, you should read the manufacturer’s instructions on frequency of use and how much to apply,” Shaver adds.

They can work, with some caveats. It’s key to choose your product carefully. “I’m generally skeptical of products that promise a lot of benefits and don’t provide good scientific evidence to support their claims,” says Dr. Mirmirani. “Some hair growths serums are promising, but the vast majority don’t provide strong evidence for me to recommend to my patients.”

She also stresses the importance of other, healthy lifestyle habits, such as eating a well-rounded diet, getting eight hours of sleep, making time for regular exercise, and addressing sources of stress. “These changes to your routine may be just as effective as some serums and supplements,” she says. “While these behaviors can be difficult to implement or difficult to stick with, they are free—and will have benefits far beyond hair growth.”

Experts agree that naturally derived serums are excellent for those seeking gentler solutions or enhancing an overall haircare routine. However, more intensive interventions may be necessary in chronic or advanced hair loss cases.

“Plant-derived serums can offer meaningful benefits, particularly when they support a healthy scalp environment, which is essential for hair growth,” says Dr. Gratch. “However, those with clinically significant hair thinning or pattern hair loss, more evidence-based options such as minoxidil or low-dose topical finasteride tend to have stronger clinical backing.”

According to Dr. Murphy-Rose, that doesn’t mean natural serums should be dismissed altogether. “Recent data has shown that some plant-derived hair growth serums may have similar efficacy as synthetically derived counterparts,” she explains. “For example, data suggests that rosemary oil and pumpkin seed oil have similar effects as topical minoxidil (a.k.a. Rogaine).” No matter which route you choose, consistency is key—results require patience, not instant gratification.

• Brendan Camp, MD, is double board-certified in dermatology and dermatopathology and sees patients at MDCS Dermatology in New York.
• Dr. Gretchen Frieling, MD, is a Harvard-trained, triple board-certified dermatopathologist with practices in Boston and Cape Cod, with over 18 years of experience in medicine, dermatopathology, and aesthetics.
• Dr. Noah Gratch, MD, FAAD is a board-certified dermatologist who specializes in treatments for acne, eczema, hyperhidrosis, rosacea, psoriasis, and skin cancer.
• Jennifer Korab is a professional hair stylist and colorist. Korab is also the founder of Renaissance Salon & Spa.
• Dr. Paradi Mirmirani is a board-certified dermatologist who specializes in hair disorders with Kaiser Permanente in Vallejo, CA
• Blair Murphy-Rose, MD, FAAD is an award-winning cosmetic and medical dermatologist and founder of Skincare Junkie. She specializes in facial rejuvenation at Newport Beach Dermatology and Plastic Surgery, while serving as clinical instructor of dermatology at Cornell.
• Dr. Christine Shaver is a board-certified dermatologist who specializes in hair restoration at Bernstein Medical Center in New York, NY.