DHT Blockers for Hair Loss: Which Ones Work, and Are They Safe?
Last reviewed on 25 July 2026. We review our treatment guides every six months to keep them accurate.
Hair loss in men and women is often driven by a hormone called dihydrotestosterone (DHT). DHT blockers are the group of treatments that either lower DHT or stop it acting on the hair follicle. This guide is the overview hub for the topic: what DHT blockers are, how they block DHT in the hair follicle, which ones actually have good evidence, how safe they are, and where the natural, topical and experimental options really stand. It is general information rather than medical advice, so please speak to a medical professional about your own situation.
For an independent, regularly updated overview of male pattern hair loss and the treatments recognised for it, the British Association of Dermatologists' patient leaflet on androgenetic alopecia and the NHS guide to hair loss are good starting points, and they stay current between our own reviews.
If you take one thing from this page, take this. When people search for the best DHT blocker, the honest, evidence-based answer is that the proven DHT blockers are the prescription medicines finasteride and, off-label, dutasteride. Most supplements and shampoos sold as DHT blockers have far weaker evidence, and none of these treatments can regrow hair from follicles that have already been lost.
What are DHT blockers?
DHT blockers are substances that either reduce how much DHT the body makes, or stop DHT from binding to receptors on the hair follicle. To understand why that helps, it is worth knowing what DHT does.
DHT is made from the male hormone testosterone by an enzyme called 5-alpha-reductase, which comes in two main forms, type 1 and type 2. In people who are genetically susceptible, DHT binds to androgen receptors in scalp hair follicles and gradually shrinks them, a process called miniaturisation, so each follicle produces a finer, shorter hair until it eventually stops producing visible hair. This is the central mechanism in male and female pattern hair loss, also called androgenetic alopecia.
DHT blockers work in one of two broad ways:
- Blocking 5-alpha-reductase, so that less testosterone is converted into DHT. This lowers DHT in the blood and the scalp. Finasteride and dutasteride, and most natural blockers, work this way. These medicines are also known as 5-alpha reductase inhibitors, or anti-DHT drugs.
- Blocking the androgen receptor, so that DHT which is already present cannot bind to the follicle. Experimental topical compounds such as pyrilutamide and RU58841 work this way.
They fall into three practical groups, which the rest of this guide takes in turn: prescription 5-alpha reductase inhibitors, natural or over-the-counter blockers, and experimental compounds that are not approved.
Prescription DHT blockers: 5-alpha reductase inhibitors (anti-DHT drugs)
The prescription 5-alpha reductase inhibitors are the only DHT blockers with strong clinical evidence. As prescription medication, they are what a dermatologist usually means by an anti-DHT drug.
Finasteride
Finasteride is the best known DHT blocker. It is a specific inhibitor of type 2 5-alpha-reductase, and in the UK the 1mg tablet is licensed for male pattern hair loss in men. It lowers DHT in the blood by roughly 70 per cent, based on studies in men, and also reduces DHT in the scalp, which slows and can partly reverse miniaturisation. In clinical trials, most men kept or improved their hair over five years, whereas hair loss continued in those given a placebo.
It usually takes several months, and sometimes up to a year, before any benefit is clear, and the benefit only lasts while the tablet is taken. If it is stopped, DHT rises again and hair loss resumes, returning towards where it would otherwise have been within about 9 to 12 months. A minority of men experience sexual side effects such as reduced sex drive, erectile difficulties or changes in ejaculation, reported in around 2 in 100 men in dermatology data. Depression, anxiety and, less commonly, suicidal thoughts have also been reported, and some men report that sexual side effects have persisted after stopping. These safety points are covered in more detail below. Finasteride is not for women or children, and it is contraindicated in pregnancy because it can affect the development of a male baby.
Dutasteride
Dutasteride blocks both type 1 and type 2 5-alpha-reductase, so it lowers DHT more than finasteride does. In the UK it is licensed for an enlarged prostate rather than for hair loss, so when it is used for hair it is prescribed off-label, meaning outside the conditions it was approved for. It carries the same kind of side-effect profile as finasteride, and in May 2026 the UK medicines regulator added a precautionary warning about mood changes to dutasteride's product information because it works in the same way. Because it is more potent and is not licensed for hair, whether it is appropriate is very much a decision for a doctor.
Topical DHT blockers: blocking DHT on the scalp
A common question is whether you can block DHT in the hair follicle directly, on the scalp, without taking a systemic tablet. This is the idea behind topical anti-androgens, and it is the heart of the oral versus topical DHT blocker question.
Topical finasteride is a solution or spray applied to the scalp. It is not a licensed medicine in the UK, and although it puts far less drug into the bloodstream than the tablet, it is still absorbed and still lowers DHT in the blood, so it is not a side-effect-free version of finasteride. Our guide to topical versus oral finasteride covers the evidence in detail.
DHT-blocking shampoos are marketed on the same promise. In practice, a rinse-off product has very little contact time with the scalp, and the ingredient with the best, though still limited, evidence is the antifungal ketoconazole rather than a true DHT blocker. Our guide on whether DHT-blocking shampoos work looks at this in full.
Natural DHT blockers: do they work?
Searches for the best natural DHT blocker are common, and the honest position is that the evidence for natural options is much weaker than for the prescription 5-alpha reductase inhibitors. Several plant compounds do inhibit 5-alpha-reductase in laboratory experiments, but inhibiting an enzyme in a dish is not the same as lowering DHT in a person, or growing hair on a scalp.
- Saw palmetto (Serenoa repens) is the best known. It is thought to inhibit 5-alpha-reductase, but far more weakly than finasteride, and a systematic review in alopecia describes the clinical evidence as limited and mixed. See our guide to saw palmetto for hair loss.
- Pumpkin seed oil has one small randomised trial, in which men took a 400mg daily oil capsule, not the seeds, for 24 weeks and gained more hair than those on placebo. The trial did not actually measure DHT. See our guide to pumpkin seed oil.
- Beta-sitosterol, a plant sterol found in pumpkin seed oil and other foods, inhibits 5-alpha-reductase in the laboratory. A small 2002 trial of a botanical blend containing beta-sitosterol and saw palmetto reported improvement in some men, but it was small and has not been robustly replicated.
- Green tea catechins, and isoflavones such as biochanin A, also inhibit 5-alpha-reductase in laboratory studies, mainly the type 1 form. There is no good evidence that drinking tea or taking these compounds lowers DHT or regrows hair in people.
- Stinging nettle root is used traditionally, with little clinical evidence for hair.
For the fuller picture, see our guides to natural DHT blockers and DHT blocker foods. Natural does not mean risk-free, and it is worth telling your doctor about any supplement you take, especially if you are due to have a procedure.
Experimental and unapproved DHT blockers
Three compounds often discussed online deserve a clear, cautious note, because none of them is an approved treatment.
Pyrilutamide (Koshine 826, KX-826)
Pyrilutamide is a topical drug that blocks the androgen receptor rather than lowering DHT. It is still in clinical trials and is not licensed for hair loss in the UK, so its long-term safety and effectiveness are not yet established.
Clascoterone (Breezula)
Clascoterone (Breezula) works in the same way as pyrilutamide, blocking the androgen receptor in the scalp rather than lowering DHT through the body, so it is not a 5-alpha reductase inhibitor. It is the most clinically advanced of this topical class: in December 2025 its developer, Cosmo Pharmaceuticals, reported positive topline results from two large Phase III trials, SCALP 1 and SCALP 2, involving around 1,465 men, described as the largest Phase III programme for a topical male hair-loss treatment, with both trials meeting their primary endpoint. It remains investigational and cannot be bought for hair loss anywhere yet, and these are company topline figures rather than full peer-reviewed data. The same molecule at a lower strength is already an approved acne cream, and the company plans to seek approval in the US and Europe, with a US submission targeted for early 2027. For the latest official updates, see Cosmo Pharmaceuticals' news and press releases.
RU58841
RU58841 is an experimental androgen-receptor blocker sold online as a research chemical. It has never been approved by any medicines regulator, and it has not been through published clinical trials for safety or effectiveness in people. It should not be regarded as a treatment to try.
Are DHT blockers safe?
Whether DHT blockers are safe depends on which blocker, and on who is taking it.
Sexual and mood side effects. A minority of men taking finasteride or dutasteride report reduced sex drive, erectile difficulties or changes in ejaculation. Depression, anxiety and, less commonly, suicidal thoughts have also been reported. In 2024 the UK medicines regulator, the MHRA, introduced patient alert cards for finasteride, and in May 2026 it strengthened the warnings for finasteride and, as a precaution, for dutasteride. Anyone taking finasteride who develops low mood or suicidal thoughts is advised to stop and seek medical advice promptly. You can read the current position in the MHRA drug safety update.
Persistent side effects, sometimes called post-finasteride concerns. Some men report that sexual side effects have continued after they stopped finasteride. The regulator's own review found the evidence on whether these effects persist is mixed, but the possibility is now reflected in the product information, and it is a reasonable thing to discuss with a doctor before starting.
Women and pregnancy. This is the single most important safety point. Because DHT is needed for the normal development of a male baby, finasteride and dutasteride can interfere with that development and must not be taken by anyone who is pregnant or who might become pregnant. Finasteride is contraindicated in women in the UK, and anyone who could become pregnant should not even handle crushed or broken tablets, as a small amount can be absorbed through the skin. Our guide to DHT blockers for women covers this in full.
Natural blockers. Being natural does not guarantee safety, and supplements can interact with other medicines. Their bigger problem is usually weak evidence of benefit rather than a specific danger, but they should still be disclosed to your doctor and your clinic.
So what is the best DHT blocker?
There is no single best DHT blocker for everyone, but the evidence points clearly in one direction. For men, finasteride has the strongest evidence and a UK licence for hair loss; dutasteride is more potent but is unlicensed for hair and used off-label. For women the picture is different and more cautious, and minoxidil, which is not a DHT blocker at all, usually has the strongest evidence; see our guide to DHT blockers for women. Natural and shampoo-based blockers are, on current evidence, weak by comparison. Which option, if any, is right for you is a decision to make with a doctor or dermatologist who can weigh the benefits and risks for your situation.
Where hair transplant surgery fits
DHT blockers can slow hair loss and help protect the hair you still have, but no medicine can bring back follicles that have already been lost. In areas that are already bald, a hair transplant is the established surgical option: it redistributes healthy follicles from the back and sides of the scalp, which are naturally more resistant to DHT, into the thinning areas. Medicines and surgery are often used together, and whether either is suitable is something a clinician can assess for you.
Frequently asked questions
What is the best DHT blocker for hair loss?
The best DHT blocker is the one with the strongest evidence, which for men is finasteride, a prescription 5-alpha reductase inhibitor licensed in the UK for male pattern hair loss. Dutasteride lowers DHT more but is unlicensed for hair and used off-label. Natural blockers such as saw palmetto and the various DHT-blocking shampoos are much weaker by comparison. No DHT blocker regrows hair from follicles that are already lost, and whether any of them is right for you is a decision to make with a doctor.
Are DHT blockers safe?
For many men, finasteride and dutasteride are well tolerated, but they do carry recognised risks. A minority of men report sexual side effects, and depression, anxiety and suicidal thoughts have been reported, which is why the MHRA introduced patient alert cards for finasteride in 2024 and strengthened the warnings in 2026. They must never be taken by anyone who is pregnant or could become pregnant. If you are considering a DHT blocker, discuss the risks and benefits with a medical professional first.
Are DHT blockers safe for women?
For women this is the most important safety point. Finasteride and dutasteride are not licensed for female hair loss, and because DHT is needed for the normal development of a male baby, they must not be taken by anyone who is pregnant or who might become pregnant. Anyone who could become pregnant should not even handle crushed or broken tablets, as a small amount can be absorbed through the skin. The evidence for these medicines in women is weak, and the treatment with the strongest evidence in women is usually minoxidil, which is not a DHT blocker. Our guide to DHT blockers for women covers this in full.
What is the best DHT blocker for women?
In women, DHT blockers are not the clear answer they can be for men. Finasteride and dutasteride are not licensed for female hair loss, the evidence in women is weak, and they carry serious risks in pregnancy. The treatment with the strongest evidence in women is usually minoxidil, which is not a DHT blocker. Female hair loss also has many treatable causes worth checking first. This is also the honest answer for anyone searching for the best DHT blocker for females. Our guide to DHT blockers for women explains this in detail.
Do topical DHT blockers work?
People often ask whether DHT can be blocked on the scalp alone. Topical finasteride is applied to the scalp and does put less drug into the bloodstream than the tablet, but it is still absorbed and still lowers blood DHT, so it is not free of the same risks, and it is unlicensed in the UK. DHT-blocking shampoos are limited by their very short contact time. There is no way to block DHT purely at the follicle with no effect elsewhere.
What are the side effects of blocking DHT?
With the prescription blockers, the main reported side effects are sexual, including reduced sex drive, erectile difficulties and changes in ejaculation, in a minority of men. Depression, anxiety and suicidal thoughts have been reported, and some men report side effects persisting after stopping. In women, the overriding concern is harm to a developing male baby in pregnancy. Natural blockers have fewer documented side effects, largely because their effects are weaker overall.
Are DHT blockers available in the UK?
In the UK, finasteride is the only DHT blocker licensed specifically for hair loss, as a 1mg tablet for male pattern hair loss in men. Dutasteride is licensed for an enlarged prostate rather than hair loss, so when it is used for hair it is prescribed off-label. Topical finasteride is not a licensed medicine in the UK, and experimental compounds such as clascoterone, pyrilutamide and RU58841 are not approved for hair loss anywhere yet. Which option, if any, is right for you is a decision to make with a doctor.
What are the big three for hair regrowth?
The big three is a popular online term for combining finasteride, minoxidil and a ketoconazole shampoo. Only finasteride is a true DHT blocker; minoxidil is a hair growth stimulant that does not act on DHT, and ketoconazole is an antifungal with limited evidence in hair loss. It is not an official medical protocol, and any combination should be discussed with a doctor rather than self-prescribed.
Do natural DHT blockers really work?
Some natural compounds, such as saw palmetto, beta-sitosterol and green tea catechins, inhibit 5-alpha-reductase in laboratory tests, but the clinical evidence that they lower DHT or regrow hair in people is limited, mixed or absent. They are far weaker than the prescription blockers. They are not harmful for most people, but they should not be relied on in place of a proper assessment, and any supplement should be mentioned to your doctor.
The bottom line
DHT sits at the centre of pattern hair loss, so blocking it is a sensible target, but the treatments vary enormously in how well they work and how safe they are. The proven DHT blockers are the prescription 5-alpha reductase inhibitors, finasteride and, off-label, dutasteride, and they come with real benefits and real risks that are worth understanding before starting. Natural and shampoo-based blockers are much weaker on the evidence, and experimental compounds such as RU58841 are not approved and should not be treated as options. No DHT blocker can restore follicles that are already gone. If your hair loss is bothering you, the most useful next step is a proper assessment by a doctor or dermatologist who can talk you through the options that genuinely fit your situation.
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