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DHT blockers: which ones actually work (and which ones don't)?
DHT plays a major role in hereditary hair loss. That is why many supplements and shampoos are marketed as "natural DHT blockers." However, the scientific evidence for these is very weak. Finasteride has been extensively studied in large, placebo-controlled trials and is proven to be effective against hereditary hair loss. For products like saw palmetto and pumpkin seed oil, the existing studies are mostly small and methodologically weak, often with industry involvement. The conclusion is therefore clear: finasteride is a proven treatment; natural DHT blockers are not.
What is a DHT blocker?
A DHT blocker is a substance that reduces the production or activity of dihydrotestosterone (DHT) . Finasteride does this by inhibiting the enzyme 5-alpha-reductase, which converts testosterone into DHT.
However, the term "DHT blocker" is also used for supplements and shampoos that have not been convincingly shown to lower DHT levels in the scalp enough to slow down hair loss in humans.
| Treatment | What does research show? | Verdict |
|---|---|---|
| Finasteride | Several large randomised studies and data covering up to five years show it demonstrably slows hereditary hair loss. | Proven effective |
| Saw palmetto | Only small and methodologically weak studies, some with commercial involvement. The effect has not been convincingly confirmed independently. | Not proven |
| Pumpkin seed oil | Nearly all claims rest on one small, short, manufacturer-funded study without convincing replication. | Not proven |
| Ketoconazole shampoo | No convincing evidence that it inhibits DHT sufficiently or stops hereditary hair loss on its own. Useful for certain scalp conditions. | No proven DHT treatment |
Kort samengevat: finasteride is wetenschappelijk bewezen tegen erfelijke haaruitval. Voor de veelverkochte natuurlijke alternatieven ontbreekt overtuigend klinisch bewijs.
Prescription DHT blocker
Finasteride
Finasteride is the best-researched DHT blocker for male pattern hair loss. It primarily inhibits type II of the 5-alpha-reductase enzyme, thereby lowering DHT levels in the blood and scalp.
Its effectiveness is not based on a single small study, but on multiple large, randomized, and placebo-controlled trials. In studies lasting up to five years, finasteride resulted in the maintenance and improvement of hair, while the placebo group continued to lose hair. Finasteride is registered in the Netherlands for the treatment of hereditary hair loss in men.
You can read about how finasteride works, what research shows regarding its effectiveness, and what the known side effects are on our page about finasteride.
Natural DHT blockers: marketing ahead of the evidence
It is often claimed that natural DHT blockers "do about the same thing as finasteride, but without the side effects." There is no real evidence for this.
Some plant extracts may show an effect on 5-alpha-reductase in laboratory settings. That does not prove that a supplement sufficiently inhibits DHT in humans, stops hair follicle miniaturization, or prevents visible hair loss in the long term. For that, high-quality, independent, and long-term clinical trials are required.
Saw palmetto
Saw palmetto is probably the best-known supplement sold as a natural DHT blocker. However, the evidence is weak.
A frequently cited placebo-controlled pilot study ultimately evaluated only ten men who received the active treatment. Six of them were assessed by researchers as having "improved." A study with such a small group cannot provide a reliable conclusion regarding average efficacy.
The honest conclusion: saw palmetto has not been proven effective against hereditary hair loss and is not an equivalent alternative to finasteride.
Pumpkin seed oil
There is only one small study on pumpkin seed oil. That study has not been independently replicated and was, moreover, sponsored by the manufacturer of the product being tested.
This makes the evidence insufficiently reliable. Therefore, pumpkin seed oil cannot be considered a scientifically proven treatment for hereditary hair loss.
DHT-blocking shampoos
Ketoconazole shampoo is often referred to online as a DHT blocker. There is no convincing clinical evidence to support this.
A small, old study found some favorable changes in hair measurements, but the authors themselves noted that larger controlled trials were needed to determine clinical significance. The study did not prove that the shampoo sufficiently blocks DHT in the scalp, nor did it show that ketoconazole independently stops hereditary hair loss in the long term.
Ketoconazole can be useful for dandruff, seborrheic dermatitis, and scalp inflammation. That is different from being a proven treatment for the hormonal cause of hereditary hair loss.
What a proven DHT inhibitor does and does not do
A proven DHT inhibitor like finasteride can slow down the further miniaturization of sensitive hair follicles and, for some users, lead to thickening or regrowth. The medication does not regenerate hair follicles that have already been completely lost.
The effect only persists as long as the treatment is used. After stopping, DHT levels rise again and hereditary hair loss typically resumes its natural course.
How do you choose a treatment?
Anyone wanting to demonstrably slow down hereditary hair loss will find little value in marketing terms like "natural," "DHT-blocking," or "clinically tested." The relevant question is whether a product actually works better than a placebo in rigorous studies and whether that result has been independently confirmed.
For finasteride, this is the case. For natural DHT blockers, the current evidence is insufficient. Therefore, they cannot be honestly presented as an equivalent alternative to prescription medication.
If you want to do something about a receding hairline or a thinning crown, there are really only two honest choices: accept it or look into a proven treatment like finasteride. Convincing evidence is lacking for natural DHT blockers; in practice, they therefore mainly provide false hope and unnecessary costs.
Frequently asked questions about DHT blockers
What is the best DHT blocker against hair loss?
For male hereditary hair loss, finasteride is the best studied DHT inhibitor and is approved in the Netherlands. Its effect has been demonstrated in several large, randomised, placebo-controlled studies. Natural remedies are not a proven alternative.
Do natural DHT blockers really work?
This has not been convincingly demonstrated. There are a few positive studies on saw palmetto and pumpkin seed oil, but they are small, short, methodologically limited and often linked to the manufacturer of the product studied. The results have not been convincingly replicated independently. The term “natural DHT blocker” is therefore mainly a marketing term; these products are not proven effective against hereditary hair loss.
Does ketoconazole shampoo block DHT?
Not to a degree that has been shown to slow hereditary hair loss. A small older study found some favourable hair measurements but did not demonstrate relevant DHT blockade, and the authors themselves called for larger follow-up research. Ketoconazole can be useful for dandruff or scalp inflammation, but it is not a proven standalone treatment for androgenetic alopecia.
Are natural DHT blockers safer than finasteride?
“Natural” does not automatically mean safe. Supplements can cause side effects and interactions, and composition and dosage differ per brand. They are also far less extensively studied than finasteride. A product with fewer reported side effects but little solid research is not automatically safer; there is simply more uncertainty.
How quickly does a DHT blocker work?
With finasteride, three to six months of daily use is usually needed before shedding visibly stabilises. The result is best assessed after about twelve months. For natural DHT blockers there is no reliable timeframe, because a clinically relevant effect has not been sufficiently demonstrated.
Can you combine finasteride with minoxidil?
Yes, when a doctor considers it medically appropriate. Finasteride reduces the influence of DHT on sensitive follicles, while minoxidil stimulates hair growth. The two act on different processes and are often combined in practice. Have a doctor assess whether the combination suits your situation.
SOURCES
- Finasteride Male Pattern Hair Loss Study Group, Long-term (5-year) multinational experience with finasteride 1 mg in the treatment of men with androgenetic alopecia, European Journal of Dermatology 2002;12(1):38–49.
- Leyden J et al., Finasteride in the treatment of men with frontal male pattern hair loss, Journal of the American Academy of Dermatology 1999;40(6):930–937.
- Prager N et al., 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, Journal of Alternative and Complementary Medicine 2002;8(2):143–152.
- Rossi A et al., Comparative effectiveness of finasteride versus Serenoa repens in male androgenetic alopecia: a two-year study, International Journal of Immunopathology and Pharmacology 2012;25(4):1167–1173.
- Sudeep HV et al., Oral and topical administration of a standardized saw palmetto oil reduces hair fall and improves hair growth in androgenetic alopecia subjects, Clinical, Cosmetic and Investigational Dermatology 2023;16:3251–3266.
- Cho YH et al., Effect of pumpkin seed oil on hair growth in men with androgenetic alopecia: a randomized, double-blind, placebo-controlled trial, Evidence-Based Complementary and Alternative Medicine 2014;2014:549721.
- Piérard-Franchimont C et al., Ketoconazole shampoo: effect of long-term use in androgenic alopecia, Dermatology1998;196(4):474–477.
- Summary of product characteristics for finasteride 1 mg, CBG-MEB.
- Pharmacotherapeutic Compass, finasteride and dutasteride, National Health Care Institute.
