Saw palmetto has been tested two ways at once: swallowed as a capsule by some volunteers and rubbed into the scalp by others, within the same clinical trial. Both versions did better than placebo. So no, I’m not going to crown a winner here. The data doesn’t split that neatly, and I’d be a little wary of any article that claims it does.

It does show that the two routes behave differently once they’re in your body, or on it. Those differences end up being a better guide to choosing than any headline percentage.

What DHT does to a follicle

Picture a follicle that’s sensitive to DHT as one that comes back a little smaller every time it restarts. The hair it grows early on is thick and long. A few cycles later it’s producing something finer and shorter, and eventually some follicles manage only wisps you can barely see. There’s a name for that shrinking, miniaturization, and it’s what drives androgenetic alopecia. Men usually see it first at the hairline and the crown. Women more often notice their part getting wider.

Where does DHT come from? Mostly testosterone, converted by an enzyme with the clunky name 5-alpha reductase. Slow that enzyme down and you have a “DHT blocker.” Finasteride, the prescription pill that Hims and Keeps build their programs around, does this very well. It also needs a prescription and carries a list of possible side effects, and a lot of people would rather try something milder first.

Most of them land on saw palmetto (Serenoa repens). In lab work it inhibits both forms of the enzyme, far more weakly than finasteride does. You’ll often find pygeum on the same label, an extract from the bark of an African cherry tree, though most of what’s known about pygeum comes from prostate research rather than hair studies.

One extract, two routes

The trial I mentioned was run at a medical institute in Bengaluru, India, and published in 2023 in Clinical, Cosmetic and Investigational Dermatology. Eighty men and women aged 18 to 50, all with mild-to-moderate pattern loss, were split four ways. Twenty took a 400 mg saw palmetto capsule every day. Another twenty applied 5 mL of a lotion made with 20% of the same extract. The other forty got a placebo version of one or the other.

Sixteen weeks later, hair fall in the capsule group was down by as much as 29%. In the lotion group it was down about 22%. You might think that settles it for the pill, until you look at density, which went the other way: up roughly 7.6% with the lotion, about 5.2% with the capsule.

Then there’s the measurement I find most telling. Only the oral group was reported to show a marked drop in DHT in the blood. A capsule gets absorbed and circulates, so it reaches your scalp because it reaches everything else too. A lotion mostly stays where you rub it in.

Notice how small those groups were. The comparisons also ran between each treatment and its own placebo, never capsule against lotion directly, so the 29% and the 7.6% can’t really be lined up like scores in a match. What you can take from the trial is that both routes helped. Which one helps more is a question it wasn’t built to answer.

Taking it by mouth

Two years is a long time to take anything every day, which is part of what makes a 2012 Italian study worth knowing about. One hundred men with pattern loss were divided between 320 mg of saw palmetto daily and 1 mg of finasteride. By the end, 38% of the saw palmetto group had more hair growth. With finasteride, 68% did.

That’s a clear win for the drug, no argument. For a botanical, though, I don’t think 38% over two years is something to wave away. The researchers also paid attention to where each treatment worked. Finasteride helped at the front of the scalp and the crown alike, while saw palmetto’s gains were mostly at the crown.

The broader picture comes from a 2020 review in Skin Appendage Disorders, put together by dermatologists at UC Irvine. Seven studies made the cut, five of them randomized, some testing capsules and some testing topicals. Between them they reported better hair quality, higher counts, and greater density, and nobody reported a serious side effect. The authors were upfront about a limitation, which I’ll pass along. Many of those products blended saw palmetto with other ingredients, so you can’t always tell what did the work.

Pygeum runs into exactly that problem. Its best hair evidence is a 2016 trial in 40 postmenopausal women, who took either a placebo or a capsule combining pygeum with saw palmetto for 16 weeks. The capsule group ended up with more hairs in the growing phase and fewer in the resting phase, significantly more than placebo did. With two botanicals in one capsule, nobody can hand the credit to either one.

So why choose the pill? Mostly because it asks so little of you. You swallow it with breakfast and you’re done, and since it circulates, every follicle gets the same exposure, which helps when thinning is spread over the whole top of the head instead of sitting in one spot.

The circulating part cuts both ways, of course. Something able to lower blood DHT is doing hormonal work well beyond your scalp. Most healthy adults tolerate saw palmetto without trouble. Pregnancy is the big exception. The Merck Manual’s position is that women who are pregnant, could become pregnant, or are breastfeeding shouldn’t take it at all. I’d put anyone on hormone-related medication on the list of people who should run it past their doctor first.

Putting it on the scalp

Fifty men in a Thai pilot study used topical saw palmetto products for 24 weeks, and their average hair counts were up at both week 12 and week 24. What happened in between is the instructive part. They used a concentrated serum daily for only the first four weeks before switching to milder products, and some of the early gains had flattened out by the end. The authors’ read was that people probably need to stay on the stronger product to keep the benefit. With no placebo group, it’s weaker evidence than the Bengaluru trial, but I think the lesson about consistency applies to any topical.

Is there a reason to go through the scalp rather than the stomach, beyond personal taste? The clearest evidence comes, oddly enough, from a drug. A 2022 European phase III trial put a finasteride spray up against finasteride tablets in 458 men, and hair counts improved by similar amounts. Blood DHT is where they parted ways. It fell 34.5% with the spray and 55.6% with the pill.

Saw palmetto isn’t finasteride, and I wouldn’t borrow those numbers for it. The principle travels, though: apply a DHT blocker to the scalp, and more of the action stays there.

Living with a serum is a different commitment. You have to remember it every day, and it only reaches the areas you actually cover, so someone thinning across the whole crown and front has a lot more ground to work than someone watching one spot near the part. Irritation is possible too, as with anything you leave on your scalp. If it shows up, stop, rather than hoping your skin gets used to it. Then there’s the upside, which for some people decides everything: less of the active ingredient is likely to end up circulating. Women who are planning a pregnancy, or might be, often find that worth the extra daily step.

The verdict at a glance

	Serum	Supplement
Reaches	Mostly the scalp, where applied	Whole body, scalp included
Blood DHT	Likely little change (going by topical finasteride data)	Fell in the 2023 oral group
Best 2023 result	Density, up about 7.6%	Hair fall, down up to 29%
Routine	Apply and massage in, daily	One capsule
Watch for	Missed days, irritation	Not for pregnancy or breastfeeding

Picking yours

If you might get pregnant in the next few years, the serum is the easier call. Mention it to your doctor all the same, and don’t start the capsule without that conversation. Women, for what it’s worth, were part of the Bengaluru trial, and the pygeum combination study enrolled only women, so this isn’t men-only territory.

Simplicity points the other way. Someone whose thinning is spread evenly across the top of the head, and who knows from experience that a daily scalp routine won’t last past week three, may get more real-world benefit from a capsule they’ll actually take every day.

Many people end up using both. I don’t see a problem with that, and a lot of personalized regimens, ours included, pair a topical with a supplement. Most outside studies have tested one route at a time, which is why we tested the combination ourselves. More on that below.

Don’t judge either one at week six. Both main trials took their key measurements at 16 weeks, which is roughly four months, and hair simply doesn’t move faster than that.

Some hair loss shouldn’t go anywhere near a botanical until a dermatologist has looked at it. That includes shedding that comes on suddenly and heavily, and round, smooth bald patches. A scalp that itches, burns, or flakes belongs in the same category. None of it looks like the slow, mild-to-moderate pattern loss that saw palmetto has actually been studied in.

Where MDhair fits

MDhair’s two products in this comparison map directly onto the two routes. Restore Serum ($44) is a leave-on scalp serum and one of our DHT-blocker formulations, with topical saw palmetto as part of its formula. It also belongs to our bond-building Restore line, so it’s designed to strengthen strands against breakage while it works at the scalp.

Regrowth Supplements ($42) are the oral side, combining saw palmetto and pygeum with more than 20 vitamins and plant-based complexes. Neither one requires a prescription, which is the main difference between MDhair’s approach and the finasteride-based programs most telehealth brands lead with.

Using both routes at once makes sense on paper. A capsule reaches every follicle through the bloodstream, and a serum adds a concentrated dose right where the thinning is, so together they cover the whole scalp and give the problem areas extra exposure without raising the oral dose. Each one also covers for the other’s weak spot. On a day you skip the serum, the supplement is still working, and the serum keeps acting on the scalp while the capsule handles thinning that’s spread out. That’s the thinking behind the regimens we build at MDhair, and it’s what my team and I tested in a 24-week clinical trial published in the Journal of Drugs in Dermatology in 2025. The study enrolled 38 women with thinning hair. Androgenetic hair loss works through the same basic mechanism in men and women, so we expect the results to hold for men as well. Each participant got a kit that our AI model matched to her scalp photos and questionnaire answers. The kits combined topical serums and shampoos with oral supplements, and some also included marine collagen peptides. Of the 27 women who finished, hair growth, coverage and thickness all improved significantly. Shedding was down 37.3% at 12 weeks and 32.4% at 24 weeks. Water loss through the scalp, a sign of a weakened skin barrier, fell 61.5% and 69% over the same periods, and electron microscopy showed better hair texture. Most participants said their hair looked better overall (88.9%), their scalp felt healthier (85.2%) and their hair was less brittle (92.6%). No adverse events were reported. The study had no placebo group, and each regimen combined several ingredients, so it can’t tell you how much of the result came from the DHT blockers alone. What it does show is that a combined topical-and-oral routine was well tolerated and improved shedding, density and scalp health over six months.

Which one, or whether to combine them, depends on the kind of thinning you have and the factors in the section above. Our free AI hair and scalp assessment is built to sort that out. It starts with a short quiz and a scalp photo, and every regimen includes unlimited chat access to our dermatologist team.

A quick word on labels, since marketing in this category gets loose. Restore Serum is a cosmetic. Regrowth Supplements fall under dietary supplements, which means the FDA hasn’t reviewed the claims made for them. Neither product is a drug. Neither is intended to diagnose, treat, cure, or prevent disease, either, however this category tends to get advertised. If you’re wondering what does have drug status, in our lineup it’s only minoxidil, approved over the counter for mild-to-moderate androgenetic hair loss.

And if you’re still torn between the two routes, the quiz is free, and it’s a sensible place to start.

Dr. Yoram Harth is a board-certified dermatologist and Co-Founder and Chief Medical Officer of MDalgorithms Inc., the company behind MDhair and MDacne. A magna cum laude graduate of Tel Aviv University's Sackler School of Medicine, he trained in dermatology at Rambam Medical Center and completed a research fellowship at Columbia-Presbyterian Medical Center in New York. His work spans phototherapy, photodynamic therapy, and AI-personalized skin and hair care.

Sources

1. Sudeep HV, Rashmi S, Jestin TV, Richards A, Gouthamchandra K, Shyamprasad K. Oral and topical administration of a standardized saw palmetto oil reduces hair fall and improves the hair growth in androgenetic alopecia subjects: a 16-week randomized, placebo-controlled study. Clin Cosmet Investig Dermatol. 2023;16:3251-3266. doi:10.2147/CCID.S435795

2. Rossi A, Mari E, Scarno M, et al. Comparitive effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year study. Int J Immunopathol Pharmacol. 2012;25(4):1167-1173. doi:10.1177/039463201202500435

3. Evron E, Juhasz M, Babadjouni A, Mesinkovska NA. Natural hair supplement: friend or foe? Saw palmetto, a systematic review in alopecia. Skin Appendage Disord. 2020;6(6):329-337. doi:10.1159/000509905

4. Wessagowit V, Tangjaturonrusamee C, Kootiratrakarn T, et al. Treatment of male androgenetic alopecia with topical products containing Serenoa repens extract. Australas J Dermatol. 2016;57(3):e76-e82. doi:10.1111/ajd.12352

5. Borràs Andrés JM, Piqué i Clusella N, Nieto Abad C, González J. Efficacy and safety of a dietary supplement containing a lipid co-extract from Serenoa repens and Pygeum africanum for the treatment of androgenetic alopecia (AGA) in women: results of a randomized, double-blind, placebo-controlled clinical trial. 2016;25:5-14. Universitat de Barcelona repository

6. Piraccini BM, Blume-Peytavi U, Scarci F, et al. Efficacy and safety of topical finasteride spray solution for male androgenetic alopecia: a phase III, randomized, controlled clinical trial. J Eur Acad Dermatol Venereol. 2022;36(2):286-294. doi:10.1111/jdv.17738

7. Merck Manual Consumer Version. Saw palmetto. merckmanuals.com

8. Bhardwaj V, Rodgers N, Harth O, Harth Y. Artificial intelligence-based personalization of treatment regimen for hair loss: a 6-month clinical trial. J Drugs Dermatol. 2025;24(3):233-238. doi:10.36849/JDD.8611

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