Browse the hair care aisle and you’ll find shampoos, supplements, serums and gummies promising thicker, fuller hair — and so much more. But walk down the same aisle with a cosmetic chemist or dermatologist and, well, the promises become as thin as the hair you’re hoping to save. “Most cosmetic hair growth products do not provide convincing evidence that their ingredients even affect hair follicles,” says Perry Romanowski, a cosmetic chemist and past president of the Society of Cosmetic Chemists.
These follicles are buried beneath your scalp, where the roots get a blood supply and nutrients. Everything you extract from a bottle has three obstacles to overcome before you reach them. “It must stay on the scalp long enough, cross the skin barrier in useful quantities and reach the target without being degraded,” explains Romanowski. Throw one away, and the fanciest ingredient might as well not be in the bottle.
No wonder finding something that works feels like a guessing game. But you’re not out of options. Here, experts share the five types of hair growth products they’d ignore — and the five they’d buy instead.
‘Hair Growth’ Shampoos
The promise: Caffeine and peptides can “wake up” your follicles while you shower.
The problem : Shampoos do not have the hold needed to stimulate growth.
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Many so-called hair growth shampoos rely on peptides, caffeine, or even proprietary complexes. “While some have interesting preliminary data, most of the evidence is far from strong and often comes from manufacturer-sponsored studies,” says Kelly Dobos, a cosmetic chemist and assistant professor at the University of Cincinnati. It’s not just the ingredients that give Dobos pause, but also the time spent on the head: “Contact time is one of the biggest limitations of rinse-off products,” she says. “I wouldn’t expect much help from shampoo alone.” That’s not to say shampoos are useless, she says. A quality product can “improve the condition of your scalp and the strength of your hair fibers, which reduces breakage.” (Find out which shampoos topped Yahoo’s best-tested rankings.)
High dose biotin
The promise: Topical and oral biotin can stimulate hair growth and reduce hair loss.
The problem : You are certainly not short of it.
Here’s a mic for you: “No studies have demonstrated that biotin supplementation is beneficial for hair growth in healthy individuals,” according to a 2024 study in the Journal of Clinical and Aesthetic Dermatology. And chances are you’re doing just fine when it comes to biotin, since deficiency is a rare diagnosis, according to the American Academy of Dermatology. That hasn’t stopped hair supplements from containing between 5,000 and 10,000 micrograms, compared to a recommended daily intake of 30.
“I wouldn’t accept them,” says Dr. Ronda S. Farah, a board-certified dermatologist and associate professor at the University of Minnesota. “Biotin in high doses can be harmful and even interfere with laboratory tests.” But if you have a confirmed deficiency, your doctor can tell you how much biotin you really need.
Viral batana and castor oils for scalp
The promise: Natural oils that help hair grow.
The problem : They are conditioning ingredients, not hair growth formulations
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TikTok is full of testimonials about castor and batana oils, claiming they’re nothing short of a miracle serum for hair growth — and an all-natural one at that. “This is one of those areas where marketing has far outpaced the evidence,” Dobos says. “Although castor oil is an excellent emollient that can reduce mechanical damage and breakage, there is no clinical evidence to show that it increases hair growth.” The same criticism applies to batana oil. “It’s a conditioning oil, but ‘breakage reduction’ and ‘new hair growth’ are not the same thing,” she says. Still, oils “can reduce breakage, increase volume, and help your hair look shinier and softer,” says Dobos — “and these changes can happen after just one use.” So all is not lost. Just the growth part.
Rice water
The promise: A centuries-old beauty secret – now in a $12 spray bottle.
The problem : You’re paying for something that doesn’t grow hair that you could make for free.
Legend has it that rice water – the starchy liquid you get after soaking or cooking rice – helped Asian royals grow floor-length hair. Even today, it is cited as one of the reasons why a city in China holds the record for “the village with the longest hair in the world”. Legend is the key word. There’s actually “no strong evidence that rice water helps hair growth,” says Farah. It’s said to condition your hair and prevent breakage, but Farah warns that “starchy buildup can leave your hair dry.” And if you have scalp irritation, like eczema or psoriasis, you risk making it even worse. This is all worth knowing before you pay $12 for a premix in a spray bottle — or start emptying your rice cooker.
Plants “natural DHT blockers”
The promise: Herbal extracts naturally block the hormone responsible for hair loss.
The problem : DHT blocking works – in a prescription medicine, not in a bottle of herbs.
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DHT is a real hormone responsible for hair loss in men, and there is a real drug that blocks it: Finasteride, also known by the brand name Propecia. So the idea that natural over-the-counter ingredients like red clover and burdock can do the same is appealing, to say the least. But at present, “there is little convincing human evidence that burdock blocks DHT in a clinically meaningful way,” says Dr. Sejal Shah, a board-certified dermatologist and founder of SmarterSkin Dermatology in New York. “It is not a stand-alone solution for hair loss.” And for women, the principle is even more fragile, since scientists have no idea to what extent DHT causes their hair loss.
Are there any hair growth products that are really worth your money?
Yes! But first, if you’re legitimately losing your hair, make an appointment with a board-certified dermatologist, trained to detect vitamin deficiencies that can affect hair, as well as conditions like thyroid disease and alopecia areata. A diagnosis changes what you should buy – and sometimes means you shouldn’t buy anything over-the-counter at all. Once you know what you’re dealing with, here’s what the evidence actually supports, cheapest first.
Minoxidil 5%, as little as $5 per month
Every expert we spoke to shouted minoxidil. “Topical minoxidil is the best-supported over-the-counter option for common hair loss,” says Romanowski. It’s also, as Dobos notes, “really the only ingredient with regulatory approval” — because hair growth is a drug claim, not a cosmetic claim. And since it’s a medicine, you can be sure that the generics contain the same active ingredient. Just make sure you get the 5% version. In a landmark 48-week clinical trial, men using 5% minoxidil experienced approximately 45% greater hair regrowth than those using 2%.
Anti-dandruff shampoo, as low as $11 a bottle
Dandruff is much more than a flaky nuisance. “A healthy scalp provides the environment follicles need to function optimally,” says Shah. And dandruff is on her list of scalp problems that “may contribute to increased hair loss and poorer hair quality.” Don’t expect it to grow anything back: “Improving scalp health alone will not reverse underlying hair loss conditions such as androgenetic alopecia,” she says. (Read our direct review of a popular anti-dandruff shampoo.)
Rosemary oil, $9 per bottle
This plant was actually the subject of a comparative trial: rosemary oil applied daily as well as a 2% minoxidil over six months. Although the study was not placebo-controlled, only included men, and did not examine the stronger 5% version, our own tester’s hair density improved from 1 in 5 to 3 after three months, enough to make it the budget choice in our own test of oils and serums. Read our full Mielle Rosemary Oil review.
Leave-in serums, starting at $50
Like a medicated anti-dandruff shampoo, a serum works on your scalp, except it doesn’t rinse off. This still won’t give you new follicles; nothing will. But after 3-4 months of testing, these three landed among our top performers, with Briogeo’s Destined for Density coming out on top — its tester was the only one to report a thicker ponytail.
A multi-ingredient supplement, $25 to $65 per month
A 2022 JAMA Dermatology The review of 30 studies found that a handful of supplements, including Viviscal and Nutrafol, were more effective than a placebo. The catch: Almost all of the research was funded by the company that sells the pill. Before you splurge, the Mayo Clinic suggests considering a multivitamin. (These are our best-tested picks.) If you’re interested in trying a hair supplement, Viviscal produced the largest density gain of the 20+ products we tested. Nutrafol has also done some good, but since it contains 3,000 micrograms of biotin, talk to your healthcare provider before starting.
Meet our experts
Perry Romanowskicosmetic chemist and past president of the Society of Cosmetic Chemists
Kelly Dobos, MSc, Cosmetic Chemist and Assistant Professor at the University of Cincinnati
Ronda Farah, MD, associate professor in the Department of Dermatology at the University of Minnesota and spokesperson for the Skin of Color Society
Sejal Shah, MD, board-certified dermatologist and founder, SmarterSkin Dermatology, New York City
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Our health content is for informational purposes only and does not constitute professional medical advice. Consult a healthcare professional with any questions regarding your health.
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