For the strongest possible DHT reduction, finasteride has the deepest evidence, but it comes with a side-effect list that now includes warnings from both the FDA and Europe’s medicines agency. For someone who’d rather not take a hormone-altering prescription, saw palmetto leads a group of natural blockers with real human trials behind them and a far gentler safety record. I’ve ordered everything below by how much trial data each option has, and added what each one can do to your body besides your hair.

Why blocking DHT helps

Most blockers here work by slowing 5-alpha-reductase, the enzyme that turns testosterone into dihydrotestosterone (DHT), usually the hormone behind a part that looks a little wider every year. In follicles with an inherited sensitivity, it causes a little shrinkage with each growth cycle, the process dermatologists call androgenetic alopecia. A few blockers act a step later, by keeping DHT from binding to the follicle.

The ranking at a glance

Option	How it works	Best human evidence	Main trade-off	Side effects
Finasteride	Enzyme blocker, lowers DHT body-wide	Two-year trials	Prescription only	Sexual problems (low libido, erectile and ejaculation issues), sometimes persisting after stopping; depression and suicidal thoughts on FDA and EU labels; breast tenderness; reduced fertility; lowers PSA. Not for women who are or may become pregnant.
Minoxidil	Not a DHT blocker	Many trials, pooled	Used daily	Scalp itching, early temporary shedding, unwanted facial hair
Saw palmetto	Slows the enzyme	Several, one vs finasteride	Milder effect	Mild and uncommon, mostly stomach upset
Pumpkin seed oil	Likely enzyme effect	One controlled trial	Less studied	Minimal: a few cases of itching or mild stomach discomfort
Rosemary	Enzyme and receptor effects	One trial vs minoxidil	Topical only, one trial	Less scalp itching than minoxidil in its trial
Pygeum, nettle	Same androgen pathway	Prostate research	Hair trials still to come	Mild, similar to placebo in prostate trials

Pharmaceutical options

Finasteride, the strongest DHT blocker

In the two trials that won finasteride its FDA approval for hair loss, men on 1 mg a day had about 107 more hairs than the placebo group after a year, counted in a one-inch circle at the crown. By two years the gap had grown to about 138 hairs, and both the men’s own ratings and their investigators’ ratings favored finasteride. Keith Kaufman and colleagues reported those results, for more than 1,500 men, in the Journal of the American Academy of Dermatology in 1998.

Because it blocks the form of 5-alpha-reductase that dominates in the scalp, finasteride lowers DHT throughout the body, not just at the follicle. That systemic effect is why it’s a prescription drug, and it’s where its side effects come from.

The side effects of finasteride

This is the part of the finasteride conversation that too often gets skipped, so I’ll lay it out plainly.

Sexual side effects. The approval trials put the rate at 3.8% of men on finasteride reporting decreased libido, erectile dysfunction or ejaculation problems, compared with 2.1% of men on placebo. Those numbers come from a year of carefully screened volunteers. The FDA label later added reports of sexual dysfunction that continued after men stopped the drug, including erectile, libido, ejaculation and orgasm problems. Some patients and clinicians call this lingering cluster post-finasteride syndrome.

Mood and suicidal thoughts. In 2022 the FDA had suicidal ideation and behavior added to the Propecia label, next to the depression it already listed, and Europe followed in 2025, when the European Medicines Agency’s safety committee, after an EU-wide review, confirmed suicidal thoughts as a side effect of finasteride tablets. Every pack of 1 mg finasteride in the EU now carries a patient card warning that sexual problems may contribute to mood changes.

Other effects on the body. The label also lists breast tenderness and enlargement, testicular pain, male infertility and poor semen quality, along with reports of male breast cancer. One effect is easy to miss: finasteride lowers PSA, the blood test used to screen for prostate cancer, so if you take it, your doctor needs to know before reading that result.

Pregnancy. Because finasteride can affect the development of a male fetus, women who are or could become pregnant shouldn’t take it, or even handle crushed or broken tablets.

Regulators still judge that the benefits outweigh the risks for approved uses, and many men take it without trouble. But anyone considering it should go in knowing the full list, and should stop and see a doctor at the first sign of sexual or mood changes.

Minoxidil, which works by a different route

When I explain minoxidil, I start with the fact that it does nothing to DHT. It works at the follicle, keeping hairs growing longer and helping shrunken follicles recover, with hormone levels left alone.

How reliable is it? When Areeba Adil and Marshall Godwin combined the placebo-controlled trials into one analysis in 2017, minoxidil beat placebo in every group they looked at, from the 2% strength women use to the 5% strength for men.

I include it in this ranking because it’s the other FDA-approved option most people weigh against natural blockers, and because it pairs well with them, one working on the follicle while the other works on the hormone. What I warn new users about is mostly on the skin, some scalp itching and a little unwanted facial hair, plus a few weeks of extra shedding as resting follicles restart.

The natural options, by strength of evidence

Saw palmetto, with the most trials behind it

In Rome, a team at Sapienza University did what most people wish someone would do, and put saw palmetto directly against finasteride for two years. They split 100 men between 320 mg of saw palmetto a day and 1 mg of finasteride, and in 2012 reported improvement in 68% of the finasteride group and 38% of the saw palmetto group.

That result is usually quoted as a loss for saw palmetto. Most of the other men on saw palmetto simply stopped losing hair over those two years, with regrowth mainly at the crown. For someone who doesn’t want a prescription, I’d count holding steady with a good chance of improvement as a solid result.

Beta-sitosterol, a plant sterol, seems to help it along. When the two were combined in a small 2002 trial, 60% of the men rated their hair as improved, compared with 11% on placebo.

Whether to swallow saw palmetto or apply it was tested in Bengaluru in 2023, where the same extract beat placebo both ways over 16 weeks, and the capsule cut hair fall by up to 29% while the lotion raised density by about 7.6%.

Saw palmetto also works when applied to the scalp. In a topical trial included in later reviews, hair counts in the saw palmetto group rose 17% by week 10 and 27% by week 50, compared with about 6% and 14% for the people using an inactive lotion, so the gap kept widening the longer people used it.

Natasha Mesinkovska’s group at UC Irvine pulled nine saw palmetto studies together in a 2020 systematic review covering 381 patients. Improvements showed up in pattern hair loss and in other kinds of thinning too, and side effects were few and mostly mild, such as stomach upset. Nothing in those studies resembles the sexual, mood or fertility warnings on finasteride’s label.

Saw palmetto has hormonal activity, so I’d avoid it during pregnancy or while trying to conceive.

Pumpkin seed oil

Seventy-six Korean men with mild-to-moderate pattern loss took 400 mg of pumpkin seed oil or a placebo every day for 24 weeks. Hair counts rose about 40% in the pumpkin seed oil group and about 10% in the placebo group, a difference that was statistically significant, as the Korean research team reported in 2014.

The researchers believe it works on 5-alpha-reductase, much as saw palmetto does. Side effects were minimal, limited to a couple of cases of itching or mild stomach discomfort. It’s a single trial, funded by the company that supplied the capsules, but a well-designed one.

Rosemary

Murata’s group in Japan found in 2013 that rosemary leaf extract blocked 5-alpha-reductase strongly in test tubes, and that one of its compounds kept DHT from binding to androgen receptors. Applied to mice whose hair growth had been suppressed with testosterone, it restored regrowth.

In people, the trial I’d point to is Yunes Panahi’s 2015 study in Tehran, which gave 100 men with pattern hair loss either rosemary oil or 2% minoxidil for six months. The rosemary group gained hair on a par with the minoxidil group and reported less scalp itching. That’s why I often point people with sensitive scalps toward a serum that includes it.

Pygeum and nettle

Pygeum, a bark extract from the African cherry tree, and nettle root come to hair care from prostate research, where a Cochrane review of pygeum trials found consistent improvement in urinary symptoms of an enlarged prostate, with side effects that were mild and similar to placebo. The prostate runs on the same androgen signaling as scalp follicles, which is why both now appear in hair formulas alongside saw palmetto. Dedicated hair trials are the next step for both, so I think of them as supporting ingredients in a combination rather than ones to take by themselves, and the same goes for broccoli, whose compound sulforaphane sped up the breakdown of DHT and promoted regrowth in a 2016 mouse study.

Safety side by side: finasteride vs. natural blockers

When patients ask me to compare the two, safety is usually what decides it.

Finasteride lowers DHT throughout the body, and its label now lists sexual dysfunction that can persist after stopping, depression, suicidal thoughts and behavior, breast changes, reduced fertility and a lower PSA reading. Two of the world’s main drug regulators have strengthened those warnings within the last four years.

Saw palmetto, pumpkin seed oil, rosemary, pygeum and nettle work on the same pathway more gently. Across their human trials, side effects have been few and mild, mostly stomach upset or scalp itching, and none carries a regulatory warning for sexual function, mood or fertility.

If you’re a younger man, a woman, or someone who’s had a bad experience with finasteride, I’d weigh that difference in safety as heavily as the difference in strength.

Saw palmetto vs. finasteride for hair loss

On the head-to-head data, finasteride produces more regrowth. Saw palmetto produced about half as many responders in the Rossi trial, though most men on it held steady, and it does that without the prescription or the hormone-related side effects that lead some men to stop finasteride.

If you’re a man whose crown has been thinning steadily and you want the strongest effect available, finasteride is worth a conversation with your doctor, one that covers the side effects above. A woman with a widening part is in a different position, because finasteride isn’t FDA-approved for women, and the same goes for any man set on avoiding a hormone-altering drug. For both, I’d build the plan around natural blockers with topical minoxidil.

How long you give either option matters as much as which one you pick. Finasteride’s lead over placebo kept growing into the second year of the Kaufman trials, and the saw palmetto groups in both the Rossi trial and the topical study looked better the longer people stayed on treatment, so I’d allow at least six months before judging any of them.

The bottom line: I’d pair saw palmetto with minoxidil for most people who want to treat pattern hair loss effectively without finasteride’s side-effect risks.

Which approach fits you

A 28-year-old whose temples have started creeping back, and who would rather not take a prescription drug, is the person I picture first for natural blockers. Saw palmetto taken daily, with topical minoxidil on the scalp, gives him two mechanisms from the start without putting his sexual health or mood on the line. I’d ask him to take a photo of his hairline on day one and judge at six months, since that’s how long most of these trials ran before results were clear.

For a woman in her mid-40s whose part has been widening for a couple of years, the plan looks similar, with one extra step first. I’d want her iron and thyroid checked, because both can cause thinning that looks like pattern loss, and then a topical with natural DHT blockers alongside 2% minoxidil.

Then there’s the man who started finasteride, saw good results, and stopped because of side effects. Switching to saw palmetto won’t match finasteride’s full effect, but in the Rossi trial most men on it held their ground, and combined with minoxidil it can help him hold on to what he’s gained.

A middle path: combining routes

In a 2015 study of 450 men in China, 94.1% improved on finasteride and minoxidil together. Finasteride alone reached 80.5% and minoxidil alone 59%, which shows how much two different routes can add to each other.

The same principle works with natural blockers. Using minoxidil on the follicle and a natural DHT blocker on the hormone side gives you two mechanisms without a prescription and without finasteride’s systemic side effects, which is the approach MDhair’s regimens are built around.

Where MDhair fits

That two-route thinking is how we built our own formulas. Regrowth Supplements ($42) carry saw palmetto and pygeum, the top-ranked natural blocker and its prostate-research partner, with nettle and broccoli in the same capsule.

On the scalp side, Restore Serum ($44) puts saw palmetto and rosemary together with copper peptides and panax ginseng, and I’d point someone with DHT-driven thinning toward it if their scalp handles products well. Someone with a sensitive or dry scalp would usually do better with Regrowth Serum ($44), which also contains saw palmetto and rosemary.

For confirmed pattern loss, our OTC minoxidil ($24) supplies the follicle route, at 2% for women and 5% for men.

The clinical trial my team and I ran on MDhair’s personalized regimen lasted six months and appeared in the Journal of Drugs in Dermatology in 2025. We compared it with the leading hair loss supplement brand. By day 90, hair growth had improved about 2.8 times as much, and hair quality improved about 3.0 times as much.

I’ll be specific about regulation, because it’s easy to blur. Of everything we sell, minoxidil alone has OTC drug status, and only for mild-to-moderate androgenetic hair loss, while the serums are cosmetics and the supplements are dietary supplements. The FDA hasn’t evaluated what we say about those, and none of them is meant to diagnose, treat, cure, or prevent disease.

Because saw palmetto and pygeum act on hormones, the supplements aren’t meant for pregnancy, for anyone trying to conceive or breastfeeding, or for anyone under 18. Someone on hormone-related medication or blood thinners, or being treated for a thyroid condition, should run them past a doctor first, and a serum that irritates the scalp is one to stop rather than push through.

Which combination makes sense depends on what’s behind your hair loss. Our free AI hair and scalp assessment starts with a short quiz and a scalp photo, matches a regimen to what it finds, and includes unlimited chat access to our dermatologist team. You can take the assessment here.

Sources

Studies were located through PubMed and the publishing journals’ own sites.

1. Kaufman KD, Olsen EA, Whiting D, et al. Finasteride in the treatment of men with androgenetic alopecia. J Am Acad Dermatol. 1998;39(4):578-589. doi:10.1016/S0190-9622(98)70007-6
2. US Food and Drug Administration. PROPECIA (finasteride) tablets, prescribing information. Revised 2022. accessdata.fda.gov
3. European Medicines Agency. Measures to minimise risk of suicidal thoughts with finasteride and dutasteride medicines. May 2025. ema.europa.eu
4. Adil A, Godwin M. The effectiveness of treatments for androgenetic alopecia: a systematic review and meta-analysis. J Am Acad Dermatol. 2017;77(1):136-141.e5. doi:10.1016/j.jaad.2017.02.054
5. 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. PubMed
6. Prager N, Bickett K, French N, Marcovici G. A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. J Altern Complement Med. 2002;8(2):143-152. doi:10.1089/acm.2002.8.143
7. Sudeep HV, Rashmi S, Jestin TV, et al. 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
8. 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
9. Cho YH, Lee SY, Jeong DW, et al. Effect of pumpkin seed oil on hair growth in men with androgenetic alopecia: a randomized, double-blind, placebo-controlled trial. Evid Based Complement Alternat Med. 2014;2014:549721. doi:10.1155/2014/549721
10. Murata K, Noguchi K, Kondo M, et al. Promotion of hair growth by Rosmarinus officinalis leaf extract. Phytother Res. 2013;27(2):212-217. doi:10.1002/ptr.4712
11. Panahi Y, Taghizadeh M, Marzony ET, Sahebkar A. Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial. Skinmed. 2015;13(1):15-21. PubMed
12. Wilt T, Ishani A, Mac Donald R, Rutks I, Stark G. Pygeum africanum for benign prostatic hyperplasia. Cochrane Database Syst Rev. 2002;(1):CD001044. doi:10.1002/14651858.CD001044
13. Sasaki M, Shinozaki S, Shimokado K. Sulforaphane promotes murine hair growth by accelerating the degradation of dihydrotestosterone. Biochem Biophys Res Commun. 2016;472(1):250-254. doi:10.1016/j.bbrc.2016.02.099
14. Hu R, Xu F, Sheng Y, et al. Combined treatment with oral finasteride and topical minoxidil in male androgenetic alopecia: a randomized and comparative study in Chinese patients. Dermatol Ther. 2015;28(5):303-308. PubMed
15. 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

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.

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