10 Best DHT-Blocking Shampoos

Article Summary

DHT-blocking shampoos are widely available, but do they actually work? While blocking DHT is a proven strategy for treating androgenic alopecia, most evidence comes from oral medications and leave-on topicals, not rinse-off shampoos. In this article, we separate science from marketing by breaking down what DHT is, how “DHT-blocking” ingredients are supposed to work, and whether shampoos can realistically deliver results. We rank the 10 most common DHT-blocking shampoo ingredients and assess which ones, if any, are worth adding to a hair loss routine.

Full Article

Dihydrotestosterone (DHT) is a male hormone, and one of the factors that can cause androgenic alopecia (AGA). Naturally, there are many products on the market that use “DHT-blocking” ingredients and offer a “science-backed” way to improve hair loss through use of their formulation.

DHT-blocking has proven effective in treating hair loss. After all, oral finasteride is an FDA-approved medication for androgenic alopecia, and it blocks DHT by inhibiting the DHT-forming enzyme, 5-α-reductase. 

We are now seeing more haircare products incorporating “DHT-blocking” ingredients into their formulations, including shampoos. These products offer a milder option to FDA-approved medications that can be incorporated into an everyday routine. But do they really work?

With so many options on the market, sorting the science from the marketing can feel daunting. That’s why we’ve researched the evidence behind key shampoo ingredients, from speculative herbal formulas to clinically proven ingredients. In this article, we break down the 10 best DHT-blocking shampoos and assess whether they are worthy hair loss products to incorporate into your routine. 

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What is DHT and DHT-Blocking? 

DHT is an androgen, a hormone that is formed from testosterone by the enzyme 5-ɑ-reductase. It is involved in the growth of facial, underarm, pubic, and body hair. While this might sound great, DHT is also implicated in the development of pattern hair loss. 

The binding of DHT to androgen receptors causes hair follicles to shrink. It shortens their growth phase while also prolonging their non-growing phase. This leads to hair thinning and shorter hair that may fall out or stop growing. 

Those with AGA often have elevated levels of 5-ɑ-reductase, DHT androgen receptors, and DHT itself.^[1]Ustuner, E. T. (2013). Cause of Androgenic Alopecia: Crux of the Matter. Plast Reconstr Surg Glob Open. 1(7). e64. Available at: https://doi.org/10.1097/GOX.0000000000000005,^[2]Sekhavat, H., Bar Yehuda, S., Asotra, S. (2025). Using the Mechanisms of Action Involved in the Pathogenesis of Androgenetic Alopecia to Treat Hair Loss. Int J Mol Sci. 26(21). 10712. Available at: … Continue reading

DHT blockers do what their name suggests – they block DHT. To do this, they often operate in one of two ways, or sometimes a combination of both:

• They inhibit 5-ɑ-reductase, reducing the formation of DHT
• They bind to androgen receptors and block DHT binding

These are not the only ways an ingredient may act to block DHT, but they are the most common.

What Are DHT-Blocking Shampoos?

Elevated DHT is often the primary cause of a balding scalp. So, naturally, there are a plethora of products available that act to block DHT, including DHT-blocking shampoos. These shampoos are formulated with ingredients that have been shown in laboratory research or in human clinical trials to reduce DHT levels.

 

The Problem With DHT-Blocking Shampoos

A DHT-blocking shampoo may appear like a great addition to your daily routine if you are concerned about hair loss. However, shampoos may not be the best option if you have AGA, and there are several factors to consider before purchasing a shampoo that claims to support hair growth. 

Regulation

You’ve probably seen shampoos advertised as “DHT-blocking” or “clinically proven to stop hair loss.” But here’s the truth: there are currently no over-the-counter shampoos that have been clinically proven to lower DHT in humans.

That doesn’t mean the ingredients are useless; it just means the science doesn’t support the marketing claims being made.

Marketing vs. Science

Many hair loss shampoos include ingredients like:

• Saw palmetto
• Green tea extract
• Rosemary oil
• Pumpkin seed extract

Marketers label these as “DHT blockers” because some research suggests these compounds might reduce DHT, but this is where the story gets complicated.

Firstly, laboratory studies are not human studies. Much of the evidence behind these claims comes from petri dish experiments (cells in a lab) or animal models (usually mice).

For example, green tea extract might reduce androgen activity in a dish of cultured cells. But real human scalps are a completely different environment. So if something works in a lab, the safest assumption is actually that it won’t work the same way in people until proven otherwise.

This is why evidence quality is so important, and why we include evidence quality rubrics with every ingredient in our ingredient database.

Delivery Mechanism 

Even when ingredients have been studied in humans, most studies use oral supplements or leave-on topical products.

That matters because oral products circulate throughout your entire body, and leave-on topicals sit on your scalp for 12+ hours. But shampoo remains on the scalp for only 1 to 2 minutes, typically 3 to 4 times per week.

That is usually not enough time for meaningful absorption, and even if some does get in, the dose is likely small. So it’s a big leap to take results from pills or leave-on products and assume the same ingredient will work in a rinse-off shampoo.

For this very reason, we organise our product metrics by formulation at Perfect Hair Health.

Hypothesis vs. Reality

Ketoconazole shampoo is often called the “best DHT-blocking shampoo”. 

Oral ketoconazole can lower male androgens (like DHT), and ketoconazole shampoo has been shown to improve hair outcomes in patients with androgenic alopecia.^[3]Perez, H.B.S. (2004). Ketoconazole as an Adjunct to Finasteride in the Treatment of Androgenetic Alopecia in Men. Medical Hypotheses. 62(1). 112-115. Available at: … Continue reading,^[4]Khandpur, S., Suman, M., Reddy, B.S. (2002). Comparative Efficacy of Various Treatment Regimens for Androgenetic Alopecia in Men. Journal of Dermatology. 29(8). 489-498. Available at: … Continue reading,^[5]Rafi, A.W., Katz, R.M. (2011). Pilot Study of 15 Patients Receiving a New Treatment Regimen for Androgenic Alopecia: The Effects of Atopy on AGA. ISRN Dermatology. 2011. 241953. Available at: … Continue reading But we don’t actually know whether ketoconazole shampoo helps hair by lowering scalp DHT. 

It might help hair for completely different reasons, such as reducing scalp inflammation, killing Malassezia yeast, or improving overall scalp health.^[6]Prohic, A., Simic, D., Sadikovic, T.J., Krupalija-Fazlic, M. (2014). Distribution of Malassezia Species on Healthy Human Skin in Bosnia and Herzegovina: Correlation With Body Part, Age and Gender. … Continue reading,^[7]Piérard-Franchimont, C., De Doncker, P., Cauwenbergh, G., Piérard, G.E. (1998). Ketoconazole Shampoo: Effect of Long-Term Use in Androgenic Alopecia. Dermatology. 196(4). 474-477. Available at: … Continue reading

While ketoconazole shampoo appears helpful, its benefit may have little or no relationship to DHT.

The 10 Best DHT-Blocking Shampoos 

When it comes to DHT-blocking shampoos, the claims go far beyond the science. Laboratory studies do not translate to human results; supplements and leave-on products are not the same as rinse-off shampoos; and even the most promising examples are based on hypotheses, not proven evidence.

Considering this, to say that there was a particular brand of DHT-blocking shampoo that is the “best” would be incorrect. Instead, we can consider ingredients that are common to many of these shampoo products. So here, we rank the 10 most common DHT-blocking ingredients in shampoos. We dissect the science, evidence quality, and growth potential behind each of them as hair loss products, so you can decide whether these ingredients in DHT-blocking shampoos really stack up to their marketing claims. 

1. Ketoconazole Shampoo

Ketoconazole was a medication formulated to treat fungal infections, but it has also been shown to treat hair loss. Ketoconazole can inhibit 5‑α‑reductase activity and could disrupt DHT binding to androgen receptors.^[8]Hugo Perez, B. S. (2004). Ketocazole as an adjunct to finasteride in the treatment of androgenetic alopecia in men. Med Hypotheses. 62(1). 112-115. Available at: … Continue reading

Unlike many of the ingredients on this list, there is clinical evidence of ketoconazole shampoo as a product for hair loss. 

A 1998 trial of 39 participants with androgenic alopecia directed participants to apply 2% kentoconazole for six months. After six months, participants using the ketoconazole shampoo showed an increase in hair diameter, while those using a placebo shampoo showed a decrease. Hair density improvements were similar between those using the ketoconazole shampoo and a 2% minoxidil therapy.^[9]Piérard-Franchimont, C., De Doncker, P., Cauwenbergh, G., Piérard, G. E. (1998). Ketoconazole Shampoo: Effect of Long-Term Use in Androgenic Alopecia. Dermatology. 196(4). 474-477. Available at: … Continue reading

In support of this, a review summarising seven studies using topical ketoconazole concluded that ketoconazole appears to increase hair diameter and result in clinical improvement in those with androgenic alopecia.^[10]Fields, J. R., Vonu, P. M., Monir, R. L., Schoch, J. J. (2020). Topical ketoconazole for the treatment of androgenetic alopecia: A systematic review. Dermatol Ther. 33(1). e13202. Available at: … Continue reading 

Although more trials are needed, and only prescription-grade 2% ketoconazole has shown to improve hair loss, this promising clinical evidence places ketoconazole at the top of the list for DHT-blocking shampoos. 

Our evidence score – 54/100 (shampoo)

Interested in learning more about ketoconazole? Read our article.

Example ketoconazole shampoos:

• Nizoral Anti‑Dandruff Shampoo 1% Ketoconazole – $15.89
• Minoxidil Max Hair Covet Hair Restoration Shampoo – $40
• Ketoconazole 2% Medicated Shampoo – $12.50 to $47.00 (Prescription)

2. Ginseng Root Shampoo

Ginseng root is often derived from the Panax species of plant. Two different extracts of Panax ginseng root have shown to inhibit 5-α-reductase activity by 50% at certain concentrations.^[11]Murata, K., Takeshita, F., Samukawa, K., Tani, T. and Matsuda, H. (2012). Effects of ginseng rhizome and ginsenoside Ro on testosterone 5α-reductase and hair re-growth in testosterone-treated mice. … Continue reading In rats, oral administration of ginseng root has been found to reduce DHT levels, suggesting ginseng maintains its inhibitory activity against 5-α-reductase in vivo (in living organisms).^[12]Park, J. Y., Park, W. Y., Song, G., et al. (2023). Panax ginseng C.A. meyer alleviates benign prostatic hyperplasia while preventing finasteride-induced side effects. Front Pharmacol. 14. Available … Continue reading,^[13]Park, H. K., Kim, S. K., Lee, S. W., et al. (2017). A herbal formula, comprising Panax ginseng and bee-pollen, inhibits development of testosterone-induced benign prostatic hyperplasia in male Wistar … Continue reading

Clinical trials have also shown that oral ingestion of Panax ginseng was found to increase hair density and thickness over 24 weeks in those with androgenic alopecia.^[14]Kim, J.H., Yi, S.M., Choi, J.E. and Son, S.W. (2009). Study of the efficacy of Korean red ginseng in the treatment of androgenic alopecia. Journal of Ginseng Research. 33(3). 223–228. Available at: … Continue reading Notably this has limited applicability to topical application, and the study does not specify whether total hair or just terminal hairs (i.e. those that actually contribute to hair looking cosmetically dense) were included, so results should be taken with a pinch of salt. 

In another trial, Panax ginseng extracts were found to improve hair density and thickness in those with female pattern alopecia when used in combination with 3% minoxidil compared to 3% minoxidil alone.^[15]Ryu, H.J., Yoo, M.G. and Son, S.W. (2014). The efficacy of 3% minoxidil vs. combined 3% minoxidil and Korean red ginseng in treating female pattern alopecia. International Journal of Dermatology. … Continue reading. However, this was again with oral intake, not topical application, and the study appeared to lack a control group to fully validate changes.  

In the laboratory, ginseng extracts have been shown to promote hair growth in human hair follicles.^[16]Park, G. H., Park, K. Y., Cho, H. I., et al. (2015). Red Ginseng Extract Promotes the Hair Growth in Cultured Human Hair Follicles. J Med Food. 18(3). 354-362. Available at: … Continue reading However, for use topically, there is not yet any clinical evidence to indicate whether Panax ginseng is effective at stopping hair loss or supporting hair growth. 

Our evidence score – 8/100 (shampoo)

Example ginseng root shampoos:

• Neofollics Scalp Therapy Exfoliating Shampoo – $32.84
• DS Laboratories REVITA Antioxidant Hair Density CBD Shampoo – $38
• Xyon Health Performance DHT-Blocking Shampoo – $45

3. Ecklonia Cava Shampoo

Also called paddle weed, this is a marine algae found off Japan and Korea. A component of this species, dieckol, has been shown to significantly inhibit 5-ɑ-reductase activity in laboratory tests and reduce DHT levels.^[17]Kang, J. I., Kim, S. C., Kim, M. K., et al. (2012). Effect of Dieckol, a Component of Ecklonia cava, on the Promotion of Hair Growth. Int J Mol Sci. 13(5). 6407-6423. Available at: … Continue reading

In the same study, daily topical application of 0.4% Ecklonia cava for 33 days stimulated active hair growth in the hair follicles of mice.^[19]Kang, J. I., Kim, S. C., Kim, M. K., et al. (2012). Effect of Dieckol, a Component of Ecklonia cava, on the Promotion of Hair Growth. Int J Mol Sci. 13(5). 6407-6423. Available at: … Continue reading Although hair growth was not as substantial as in mice receiving 5% minoxidil, the study shows the potential of topical Ecklonia cava as a natural hair loss ingredient.

However, clinical trials in humans showing the effectiveness of Ecklonia cava as a DHT blocker and hair loss product are unfortunately absent. Until then, Ecklonia cava can only be stated as an effective DHT blocker in vitro (in the test tube).

Our evidence score – 8/100 (shampoo)

Example Ecklonia cava shampoos:

• Zenluca Hair Growth Stimulating Shampoo – €19,95 ($23.38)
• Neofollics Hair Growth Stimulating Shampoo – $32.84

4. Oleanolic Acid Shampoo

Oleanolic acid is a natural compound found in many plants, fruits, and herbs. It is a natural inhibitor of 5-ɑ-reductase. At a 2014 conference, researchers reported that formulations of 3% oleanolic acid were found to inhibit 5-ɑ-reductase by 68% and inactivated 54% of testosterone conversion to DHT.^[20]Ashtiani, H. A., Ehsani, A. H., Brikbin, B., Krimlou, Z., Pouya, F. B. (no date). Effectiveness of the formulation that containing oleanolic acid 3% on inhibition of 5-and#945; reductase activity on … Continue reading

While this report might sound positive, the research has not been submitted for peer review and publication. Thus, the robustness of these findings is questionable. 

There is, however, in vivo evidence to support the DHT-blocking activity of oleanolic acid. In a study using mice, topical oleanolic acid was found to not only promote hair growth but to also reduce the levels of 5-ɑ-reductase and DHT in blood.^[21]Zhang, B., Zhang, W., Luo, J., et al. (2023). Effects of oleanolic acid on hair growth in mouse dorsal skin mediated via regulation of inflammatory cytokines. J Appl Biomed. 21(1). 48-57. Available … Continue reading

Clinical evidence with humans is also available. In a trial examining the effectiveness of a topical hair loss lotion that included oleanolic acid, participants were found to have reduced hair shedding.^[22]Garre Contreras, A., Piquero-Casals, J., Trullas, C., Martinez, G. (2018). Efficacy and Safety of a New Topical Hair Loss-Lotion Containing Oleanolic Acid, Apigenin, Biotinyl Tripeptide-1, … Continue reading Of course, this was a multi-ingredient lotion, so it is hard to attribute this to the effect of oleanolic acid alone. However, this does suggest topical application of oleanolic acid could be promising as a hair loss ingredient, and clinical trials with an oleanolic acid shampoo are warranted.

Our evidence score – 7/100 (shampoo)

Example oleanolic acid shampoos:

• Nourkrin Shampoo – $16.53
• Keeps Thickening Shampoo – $24
• DS Laboratories RADIA Purifying Shampoo for Dry, Sensitive or Irritated Scalp – $32

5. Green Tea Extract Shampoo

Green tea is a very common herbal remedy and has a multifaceted role as a DHT blocker. 

Laboratory studies show that green tea extract can bind androgen receptors, preventing the binding of DHT.^[23]Siddiqui, I. A., Asim, M., Hafeez, B. B., Adhami, V. M., Tarapore, R. S., Mukhtar, H. (2011). Green tea polyphenol EGCG blunts androgen receptor function in prostate cancer. FASEB J. 25(4). … Continue reading This would reduce the downstream impact of DHT-mediated hair loss.

Green tea extract has also been shown to be a 5-ɑ-reductase inhibitor in test tubes. However, when testing whether green tea extract could also inhibit 5-ɑ-reductase within cells, this was found not to be the case.^[24]Hiipakka, R. A., Zhang, H. Z., Dai, W., Dai, Q., Liao, S. (2002). Structure-activity relationships for inhibition of human 5alpha-reductases by polyphenols. Biochem Pharmacol. 63(6). 1165-1176. … Continue reading,^[25]Liao, S. S., Hiipakka, R. A. (1995). Selective-Inhibition of Steroid 5 α-Reductase Isozymes by Tea Epicatechin-3-Gallate and Epigallocatechin-3-Gallate. Biochem Biophys Res Commun. 214(3). 833-838. … Continue reading 

What cell studies do show, however, is that green tea extract can dampen the downstream effects of DHT. In hair follicle cells, green tea extract can protect against DHT-induced death and lack of growth.^[26]Shin, S., Kim, K., Lee, M. J., et al. (2016). Epigallocatechin Gallate-Mediated Alteration of the MicroRNA Expression Profile in 5α-Dihydrotestosterone-Treated Human Dermal Papilla Cells. Ann … Continue reading 

The DHT-blocking mechanisms characterised for green tea appear to translate to in vivo DHT-blocking. Dietary intake of green tea, along with soy compounds, was found to reduce DHT levels in mice. However, intake of green tea alone was found to actually increase DHT.^[27]Zhou, J. R., Yu, L., Zhong, Y., Blackburn, G. L. (2003). Soy Phytochemicals and Tea Bioactive Components Synergistically Inhibit Androgen-Sensitive Human Prostate Tumors in Mice. J Nutr. 133(2). … Continue reading This suggests whole green tea, instead of green tea extract, may not effectively block DHT. 

For now, there is a lack of large, randomized controlled trials to indicate whether green tea extract, whether topical or oral, can effectively block DHT in humans. Thus, in a shampoo, its role is best considered mechanistically possible but not yet proven. 

Our evidence score – 6/100 (shampoo)

Example green tea extract shampoos:

• DrFormulas Best DHT Blocker Shampoo – $20.41
• Keeps Thickening Shampoo – $24
• Neofollics Hair Growth Stimulating Shampoo – $32.84

6. Sulforaphane Shampoo

Sulforaphane is a plant-derived compound known as a phytochemical. It is known for its antioxidant, anti-inflammatory, and even potential anti-cancer properties, and may have a novel mechanism for promoting hair growth as well. 

In the laboratory, sulforaphane has been shown to increase the concentration of an enzyme that can degrade DHT, known as 3α-hydroxysteroid dehydrogenase.^[28]Park, Y., Choi, K., Kim, H., Lee, J., Park, G., Kim, J., (2021). Sulforaphane, L-Menthol, and Dexpanthenol as a Novel Active Cosmetic Ingredient Composition for Relieving Hair Loss Symptoms. … Continue reading

But does this mean it can actually promote hair growth? In the same study, the hair growth potential of sulforaphane as a conditioner in those with androgenic alopecia was examined in an 18-week clinical trial.

The trial found that there was an 87% increase in visual hair growth at the crown and forehead line, and an increase in the number of hair follicles. While this was found to be statistically significant, it should be noted that this only translated to a difference of +2 hairs on average at 18 weeks compared to day one.

To make conclusions about the potential of sulforaphane against hair loss, we need more robust clinical trials. We also need more evidence of its use as a shampoo; the trial above used sulforaphane as a conditioner, where it would have had minimal contact with the scalp compared with a shampoo.

Figure 4: Five images per time point showing the scalp at baseline (0 week) and following use of a sulforaphane conditioner for 6, 12, and 18 weeks. Adapted from Figure 5.^[29]Park, Y., Choi, K., Kim, H., Lee, J., Park, G., Kim, J., (2021). Sulforaphane, L-Menthol, and Dexpanthenol as a Novel Active Cosmetic Ingredient Composition for Relieving Hair Loss Symptoms. … Continue reading. Image obtained in line with the Creative Commons License. 

If you want to learn more about sulforaphane for hair loss, read our article here.

Our evidence score – 4/100 (shampoo)

Currently, there are no sulforaphane shampoos on the market.

7. Melatonin Shampoo

Melatonin is not a traditional DHT blocker. It does not inhibit 5‑α‑reductase or bind with androgen receptors. Instead, melatonin appears to reduce the DNA changes that occur when androgen receptors are activated.^[30]Hao, L., Dong, Y., Zhang, J. J., et al. (2022). Melatonin decreases androgen-sensitive prostate cancer growth by suppressing SENP1 expression. Transl Androl Urol. 11(1). 91-103. Available at: … Continue reading

This has been studied in relation to prostate cancer, but it could also mean that when DHT binds androgen receptors, the receptors are not able to signal DNA changes that may result in hair loss. 

Melatonin has also been shown to reduce androgen levels in cells of the ovary.^[31]Yu, K., Wang, R. X., Li, M. H., et al. (2019). Melatonin Reduces Androgen Production and Upregulates Heme Oxygenase-1 Expression in Granulosa Cells from PCOS Patients with Hypoestrogenia and … Continue reading Although not hair follicle cells, this suggests melatonin could similarly reduce androgens (like DHT) at the scalp. 

Unfortunately, there isn’t any evidence to show that application of melatonin results in reduced blood DHT levels, but topical application of 0.1% melatonin has shown to decrease the rate of active hair loss for patients with early androgenic alopecia. However, not all results were statistically significant.^[32]Fischer, T.W., Burmeister, G., Schmidt, H.W. and Elsner, P. (2004). Melatonin increases anagen hair rate in women with androgenetic alopecia or diffuse alopecia. British Journal of Dermatology. … Continue reading 

A subsequent study analysing the results of five clinical studies using topical melatonin concluded that, overall, melatonin is an effective ingredient for androgenic alopecia. Leave-on, topical melatonin was found to not only be safe but also increase hair density, reduce hair loss, and increase hair strength.^[33]Fischer, T. W., Trüeb, R. M., Hänggi, G., Innocenti, M., Elsner, P. (2012). Topical Melatonin for Treatment of Androgenetic Alopecia. Int J Trichology. 4(4). 236-245. Available at: … Continue reading

Whether a rinse-off melatonin formula could produce similar results is not yet clear, but the topical evidence thus far indicates that melatonin could be a beneficial ingredient for androgenic alopecia.

Our evidence score – 4/100

Example melatonin shampoos:

• As I am Rosemary Shampoo – $9.99
• RevivSerums RevivHair Stimulating Shampoo – $29.00
• Kenogen Hair Growth Shampoo – $59.00 

8. Saw Palmetto Shampoo

Saw palmetto is a plant native to the United States. In the laboratory, extracts of saw palmetto have been found to inhibit the activity of 5‑α‑reductase.^[34]Blair, H. A. (2022). Hexanic Extract of Serenoa repens (Permixon®): A Review in Symptomatic Benign Prostatic Hyperplasia. Drugs Aging. 39(3). 235-243. Available at: … Continue reading,^[35]Buonocore, D., Verri, M., Cattaneo, L., Arnica, S., Ghitti, M., Dossena, M. (2018). Serenoa repens extracts: In vitro study of the 5α-reductase activity in a co-culture model for Benign Prostatic … Continue reading The effectiveness of saw palmetto has also been shown outside the lab. Oral administration of saw palmetto extracts at 320 mg per day has been shown to reduce DHT levels in male participants, confirming that saw palmetto can indeed inhibit 5‑α‑reductase when ingested.^[36]Di Silverio, F., Monti, S., Sciarra, A., et al. (1998). Effects of long-term treatment with Serenoa repens (Permixon®) on the concentrations and regional distribution of androgens and epidermal … Continue reading

In clinical trials, the topical application of saw palmetto for hair loss has received mixed results. Application of saw palmetto as a lotion has shown to marginally increase hair number compared to a placebo lotion after 50 weeks in those with androgenic alopecia.^[37]Morganti, P., Fabrizi, G., James, B., Bruno, C. (1998). Effect of gelatin-cystine and serenoa repens extract on free radicals level and hair growth. Journal of Applied Cosmetology. 16, 57-64. … Continue reading. It has also been observed that androgenic alopecia patients had improved hair strength and slightly thicker hair after application of a saw palmetto oil for 16 weeks.^[38]Sudeep, H.V., Rashmi, S., Jestin, T.V., Richards, A., Gouthamchandra, K., Shyamprasad, K. (2023). Oral and Topical Administration of a Standardized Saw Palmetto Oil Reduces Hair Fall and Improves the … Continue reading 

Based on the evidence, saw palmetto seems a promising natural ingredient for promoting hair growth. But it should be considered that both of the outlined trials appeared to count terminal hairs (i.e., long, thick hairs that contribute to hair fullness) as well as vellus hairs (i.e., fine “peach fuzz” hairs that don’t contribute to hair fullness), and use a leave-on formula, so the results are only tentative and do not justify the purchase of a rinse-off saw palmetto shampoo. 

However, the foundation is there for future clinical studies to build on these results and provide the proof-of-concept evidence needed to determine whether a saw palmetto shampoo can be effective against hair loss.

Our evidence score – 4/100 (shampoo)

Example saw palmetto shampoos:

• DrFormulas Best DHT Blocker Shampoo – $20.41
• Advanced Trichology DHT-Blocking Shampoo – $27.95
• Shapiro MD DHT Fighting Shampoo – $39.95

9. Pumpkin Seed Oil Shampoo

In the laboratory, pumpkin seed oil has been identified as a moderate inhibitor of 5-α-reductase and can interact with androgen receptors, preventing the conversion of testosterone to DHT and the binding of DHT. At 5 mg per mL, pumpkin seed oil could inhibit 5-α-reductase 70-95%.^[39]Heim, S., Seibt, S., Stier, H., Moré, M. I. (2018). Uromedic® Pumpkin Seed Derived Δ7-Sterols, Extract and Oil Inhibit 5α-Reductases and Bind to Androgen Receptor in Vitro. Pharmacol Pharm. 9(6). … Continue reading 

There are no studies demonstrating that pumpkin seed oil reduces DHT levels in humans. Administration of pumpkin seed oil extracts to rats has shown to reduce 5-α-reductase levels, showing that the outcomes of laboratory experiments in vitro are matched in vivo.^[40]Kang, X. C., Chen, T., Zhou, J. L., et al. (2021). Phytosterols in hull-less pumpkin seed oil, rich in ∆7-phytosterols, ameliorate benign prostatic hyperplasia by lowing 5α-reductase and … Continue reading

In a clinical trial of 60 women with androgenic alopecia, topical application of a pumpkin seed oil foam for three months increased the number of regrowing hairs compared to baseline, but not as much as 5% minoxidil. It should be noted that upright growing hairs aren’t the best endpoint for assessing outcomes, since these come and go with the natural hair cycle. Additionally, this study featured no placebo group, so whether these results were substantial against no treatment at all is unknown.^[41]Ibrahim, I. M., Hasan, M. S., Elsabaa, K. I., Elsaie, M. L. (2021). Pumpkin seed oil vs. minoxidil 5% topical foam for the treatment of female pattern hair loss: A randomized comparative trial. J … Continue reading

Nonetheless, the trial suggests topical pumpkin seed oil has the potential to support hair growth, but without further clinical studies, it is simply a marketing ingredient, not a science-backed one.

Our evidence score – 4/100 (shampoo)

Example pumpkin seed oil shampoos:

• BosleyMD Revive Nourishing Shampoo – $21.25
• Roman Revive Shampoo – $24
• Botanical Green Care Saw Palmetto & Cayenne Anti-Hair Loss Shampoo – $36.99

10. Rosemary Oil Shampoo

Rosemary oil is an essential oil and a common ingredient in products marketed towards hair loss. 

In the laboratory, rosemary oil extract has been found to inhibit the activity of 5-ɑ-reductase. Rosemary oil extract has also been shown to potentially prevent the interaction of DHT with androgen receptors, both effects resulting in improved hair growth in mice compared to control.^[42]Murata, K., Noguchi, K., Kondo, M., et al. (2013). Promotion of hair growth by Rosmarinus officinalis leaf extract. Phytother Res PTR. 27(2). 212-217. Available at: https://doi.org/10.1002/ptr.4712

Research is needed to test whether the same effect occurs within humans, although clinical trials with this essential oil do indicate that rosemary oil works similarly within the body.

Namely, a clinical trial with androgenic alopecia patients has shown that rosemary oil can increase hair count by a similar amount to 2% minoxidil following topical application for six months. However, while the results sound great, increases were not substantial in either group compared to baseline hair counts.^[44]Panahi, Y., Taghizadeh, M., Marzony, E. T., & Sahebkar, A. (2015). Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial. Skinmed. 13(1). … Continue reading This would suggest:

• Rosemary oil only marginally improves hair count
• There may be quality issues with the data and conclusions, as minoxidil should significantly and progressively support hair growth over this time frame.

As it stands, there is some evidence to suggest that rosemary oil might have some action on DHT, but further clinical studies are needed to validate these results and indicate whether rosemary oil could be equally as effective when applied as a shampoo. 

Our evidence score – 4/100 (shampoo)

Example rosemary oil shampoos:

• Ulo Thickening Shampoo – $21.75
• Dandrene Exfoliating Anti-Dandruff Shampoo – $32
• Neofollics Scalp Therapy Exfoliating Shampoo – $32.84

Is a DHT-Blocking Shampoo Worth It?

Unlike supplements or leave-on topical products, shampoos have a short contact time with the scalp and are rinsed off quickly. Shampoos are also often used inconsistently. This does not give ample time or enough repeated exposure for ingredients to properly absorb into the scalp and affect hair growth. 

Some DHT-blocking ingredients show promise when used topically. However, there is limited evidence, laboratory or clinical, to show that they would have the same effect in a shampoo, except for ketoconazole. 

DHT-blocking shampoos contain a range of herbal extracts that may help hair look healthier and feel softer. If you find your DHT-blocking shampoo gives your hair a physical appearance boost, feel free to keep using it. However, the evidence for the use of DHT-blocking shampoos in hair loss regimens does not stack up with claims of hair regrowth when used alone. 

If you are interested in DHT-blocking, seek out FDA-approved oral DHT blockers such as finasteride, dutasteride, bicalutamide, flutamide, or spironolactone. If you want a chemical-free formula, find topical lotions, serums, or oils with DHT-blocking ingredients instead of shampoos. Both of these formulations offer longer contact time in and outside the body. 

However, DHT-blocking shampoos could be used alongside FDA-approved hair loss treatments or leave-on products with DHT-blocking ingredients if you choose, just do not rely on these shampoos alone to treat hair loss.

Final Remarks 

When considering a DHT-blocking shampoo, ingredient choice matters more than marketing. Ingredients like ketoconazole have the best evidence behind them to support their use in an anti-hair loss product.

But it’s not just the ingredients that matter, it’s the formulation as well. DHT blockers are more often incorporated into supplements and FDA-approved medications. This allows the ingredients to work from deep inside the body. Shampoos instead rely on repeated, short-term exposure to deliver the ingredients. 

Shampoo exposure like this may influence local DHT levels at the scalp, generally improve the scalp environment, and slow the progression of androgenic alopecia, but it will not act as a re-growth formula, and use of shampoo is unlikely to resolve androgenic alopecia when used alone.