Saw palmetto has become the internet's favourite "natural DHT blocker." Search the phrase and you get a wall of before-and-after photos, a few dermatologists rolling their eyes, and a lot of people asking the same three things. Does saw palmetto for hair loss work? How does it compare to finasteride? And is it safe for women? This article answers all three from the trials, then explains where our two saw palmetto formulas fit and where they do not.
Why hair falls out in the first place
Most hair thinning in adults is androgenetic alopecia, the pattern kind. Male or female, the driver is the same molecule: dihydrotestosterone, DHT. An enzyme called 5-alpha-reductase converts testosterone to DHT in the scalp, and in people who inherit sensitive follicles, DHT shortens the growth phase and shrinks the follicle a little each cycle. Hairs get finer, then shorter, then stop. Women usually keep the hairline and thin across the crown; men lose the temples and the vertex.
Prescription treatment goes after the enzyme. Finasteride blocks about 70 % of type II 5-alpha-reductase; dutasteride blocks nearly all of it. Saw palmetto, an extract of the berries of Serenoa repens, inhibits the same enzyme, more weakly and through a different mix of fatty acids and plant sterols. That is the entire theory. It is plausible, and it has been tested in people, which is more than most hair supplements can say.
The three studies worth knowing
The 2002 pilot. Nineteen men with mild to moderate pattern loss took a saw palmetto and beta-sitosterol combination or placebo for about five months. Six of ten on the botanical improved on blinded assessment against one of nine on placebo (Prager et al., 2002). Tiny, but the first real signal.
The 2012 finasteride comparison. One hundred men with mild to moderate androgenetic alopecia took either saw palmetto 320 mg a day or finasteride 1 mg a day for two years. Thirty-eight percent of the saw palmetto group improved. Sixty-eight percent of the finasteride group did. Saw palmetto worked better at the crown than the front (Rossi et al., 2012). The study was open-label with no placebo arm, so the numbers are rougher than they look. The shape of the result has held up: real effect, roughly half the size.
The 2020 systematic review. Researchers at UC Irvine pooled five randomised trials and two prospective cohorts of oral and topical saw palmetto, 100 to 320 mg, in people with pattern loss or telogen effluvium. Across studies, 60 % of users reported improved hair quality, 27 % improved total hair count, and 83 % showed higher hair density on investigator assessment. The authors called it a possible option and asked for larger trials (Evron et al., 2020). A 2025 critical review in the International Journal of Dermatology reached a similar place, with sharper language about small samples and inconsistent extracts (Nguyen et al., 2025).
So: it does something, it does less than the drug, and the trials are small. Anyone telling you either "it does nothing" or "it is as good as finasteride" has not read them.
Saw palmetto vs finasteride
| Saw palmetto (oral, 320 mg) | Finasteride (1 mg) | |
|---|---|---|
| 5-alpha-reductase inhibition | Partial, estimated 30–40 % | ~70 % (type II) |
| Improvement in 2-year comparison | 38 % of men | 68 % of men |
| Best scalp region | Crown | Crown and front |
| Time to judge | 4–6 months minimum | 6–12 months |
| Prescription needed | No | Yes |
| Sexual side effects | Rarely reported | Reported in a minority; usually reversible |
| Effect on PSA test | No meaningful change | Lowers PSA (matters for prostate screening) |
| Evidence quality | Small trials, one open-label comparison | Large placebo-controlled trials |
| Cost | Low | Low (generic) |
Two clinical points sit inside that table. Saw palmetto does not distort the PSA blood test the way finasteride does, which some men value. And finasteride is prescribed for a reason: for a man with progressing loss who tolerates it, it is the stronger tool, and no botanical should be sold as a swap for it. A GoodRx review of the comparison lands in the same place (GoodRx).
Saw palmetto for women
This is where the questions get more careful, and the answers should too.
Female pattern hair loss is also DHT-sensitive, so the mechanism applies. The trials, though, are almost all in men. The Evron review included women, mostly in the telogen effluvium and "self-perceived thinning" studies, and the direction was the same. That is encouraging and thin at once.
The bigger issue for women is what else is in the bottle and what else is going on in the body. Hair shedding in women is very often not androgenetic at all. Low ferritin, thyroid change, a big stress event three months earlier, a new contraceptive, postpartum shift, perimenopause: each produces diffuse shedding that no DHT inhibitor will touch. A ferritin, TSH and, where relevant, androgen panel from a doctor is worth more than any supplement in the first month.
Saw palmetto is not for anyone pregnant, trying to conceive or breastfeeding. It acts on androgen metabolism, and hormonal contraception is a reason to check with a prescriber.
About the DHEA in our formulas
Both Saw Palmetto for Women and Saw Palmetto for Men pair saw palmetto with DHEA. We should be plain about what that means. DHEA is a hormone precursor the body can convert toward testosterone or oestrogen. In some people, particularly women with PCOS or with hair loss that is driven by excess androgens, DHEA can push the wrong way. Our women's formula was built around hormonal balance, skin and hair support in women past the reproductive peak, when DHEA levels have fallen; it was not built for a 25-year-old with androgen-driven thinning. If that is you, the plain saw palmetto question and the DHEA question are separate, and the second one belongs with a doctor. If the hormonal picture you are trying to fix is on the oestrogen side rather than the androgen side, that is a different molecule and a different article: DIM and Estrogen Metabolism.
The men's formula adds ashwagandha, whose trial dose for stress is 600 mg a day; check the panel for the amount in a serving and compare. Every active in both products is printed with its milligram figure, no blend, and the certificate for your lot is available by email. We wrote a guide on reading those panels in How to Read a Supplement Label.
Dose, form and how long to give it
- Dose. The oral trials used 320 mg a day of a lipidosterolic (fat-soluble) extract, usually standardised to 85–95 % fatty acids. Powdered whole berry is a different, weaker material. Look for the word "extract" and a standardisation figure.
- Form. Oral capsules are what the two-year comparison used. Topical serums have their own small literature and do not carry the hormonal considerations.
- Timing. With food. The extract is fat-soluble.
- How long. Hair grows about a centimetre a month and the follicle cycle is long. Nothing in this category can be judged before four months, and six is fairer. The finasteride comparison ran two years.
- How to judge it. Take a photo of the crown under the same light on day one and every eight weeks. Count hairs on the pillow or in the shower drain for a week at a time. "It feels thicker" is not data; a photo is.
Side effects and who should not take it
Saw palmetto is generally well tolerated. Mild stomach upset is the usual complaint. It may add to the effect of blood thinners, so warfarin and similar drugs are a reason to ask first. Rare liver reactions appear in case reports collected by LiverTox at the NIH, without a proven causal link. Stop and see a doctor if you notice yellowing, dark urine or unusual fatigue.
Do not take it if you are pregnant, trying to conceive or breastfeeding, if you are under 18, or if you have a hormone-sensitive condition without your specialist's say-so. Men on a prostate work-up should tell their urologist they are taking it, because although it does not change PSA the way finasteride does, the doctor should know.
Where it fits in a realistic plan
A supplement is the least powerful thing in a hair plan and the easiest to buy, which is why people start there. A better order:
- Rule out the reversible causes with blood work: ferritin, TSH, vitamin D, and for women an androgen panel if the pattern suggests it.
- Fix sleep and stress load; a shedding wave three months after a bad stretch is common. Our Cortisol Health sits in that part of the routine, not in the hair part.
- Decide with a doctor whether a prescription is right for you. Minoxidil works through a different mechanism and stacks with everything here.
- Add saw palmetto if you want a botanical 5-alpha-reductase inhibitor with the expectations set by the trials above.
- Photograph, wait six months, then decide.
Frequently asked questions
Does saw palmetto really block DHT?
Partially. It inhibits the enzyme that makes DHT, less strongly than finasteride. Estimates of 30 to 40 % reduction are common in reviews, from small studies.
How long does saw palmetto take to work for hair loss?
Four to six months before an honest judgement; trials ran five months to two years. Shedding often slows before regrowth is visible.
Can women take saw palmetto for hair loss?
Many do, and the mechanism applies to female pattern loss, but the trials are mostly in men. Not during pregnancy or breastfeeding, and worth a conversation if you use hormonal contraception or have PCOS.
Is saw palmetto as good as finasteride?
No. In the only two-year comparison, 38 % improved on saw palmetto against 68 % on finasteride. It is a milder option, useful for people who cannot or prefer not to take the drug.
What dose of saw palmetto for hair?
320 mg a day of a standardised lipid extract is what the oral trials used.
Does saw palmetto affect testosterone?
It lowers conversion of testosterone to DHT; it does not lower testosterone itself in trials, and sexual side effects were rare.
Conclusion
Saw palmetto for hair loss is neither a myth nor a miracle. The trials show a modest, real effect on pattern loss, roughly half the size of finasteride's, with a gentler side-effect profile and no PSA distortion. Women can use it with more caution and less evidence, and should get the reversible causes checked first. Our formulas add DHEA and, for men, ashwagandha, which suits some people and not others; the panel tells you what is in a serving, and this article tells you what the trials used. Buy on that basis, take it with food for six months, and let the photographs decide.
References
- Prager N et al. J Altern Complement Med 2002;8(2):143-52. PMID: 12006122
- Rossi A et al. Int J Immunopathol Pharmacol 2012;25(4):1167-73. PMID: 23298508
- Evron E et al. Skin Appendage Disord 2020;6(6):329-337. PMID: 33313047
These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.
