Hair loss

What is a DHT Blocker?

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Medically approved by Dr Earim Chaudry
Chief Medical Officer
iconLast updated 12 April 2024
In 30 seconds…

They are absolutely crucial to the effective treatment of hair loss, but what are DHT blockers exactly? To put it in its simplest terms, they are the medicines that block or inhibit the function of dihydrotestosterone, or DHT. And DHT is the hormone that drives male pattern baldness.

DHT is produced naturally from testosterone. However, one of its unfortunate side effects is that, once it is in your system, it can cause your hair follicles to weaken and shrink – meaning that they stop producing hair. The result can be thinning hair, or a receding hairline.

Using a DHT blocker would prevent the production of this hormone, so that your hair follicles stay healthy. Finasteride is the only DHT blocker to be proven to work, and it’s effective in over 90% of men.

DHT Blockers Defined

Hair loss is a funny thing. On the one hand, it can be a heart-breaking, even panic-inducing, emotional experience. On the other, though, it is a simple biological process that progresses despite your emotional pain.

If you are still feeling the pain of hair loss, it may help to take a look at the science. And if you take even the briefest of glances at the science, you’ll come across these things known as ‘DHT blockers.’ These are often touted as the agents that can stop that biological process in its tracks. And that’s true, as long as you find the one that works.

So, what is a DHT blocker, really? And which has the best chance of halting – or even reversing – your hair loss? To answer these questions, we need to look at the science in a little greater detail.

What is DHT?

DHT is a male sex hormone or androgen that your body creates from testosterone. However, it is much more potent than the more famous hormone. DHT plays a crucial role during puberty in men, as it helps to create the features we typically associate with adult men: facial and body hair growth, a deep voice, and increased muscle mass.

While it is a handy little hormone in many ways, DHT does produce its unwanted side effects. Hair loss – i.e. balding on the top of the head – is number one among these.

Male pattern baldness (MPB) – also known as male pattern hair loss or androgenetic alopecia – happens because the conversion of testosterone into DHT occurs, at least in part, in your hair follicles. This is all well and good, but, in the majority of men, those hair follicles are sensitive to the hormone. So, the more DHT produced, the less healthy these follicles become: high DHT levels actually causes your hair follicles to shrink and weaken – and ultimately to stop producing hair at all.

If guys need it at an early stage of life, high levels of DHT become your central antagonist in the battle of baldness. This hormone and the process it drives is responsible for 90% of baldness cases in men. That’s why men are choosing to block it.

How Does a DHT Blocker Work?

And that’s where DHT blockers come in. In short, they keep the hair on your head by targeting the production of this hormone.

DHT blockers work by inhibiting the specific enzyme – known as 5-alpha-Reductase, or 5α-Reductase – that enables the conversion of testosterone into DHT. A DHT blocker binds to this enzyme and prevents it from producing DHT. So, it’s not that it blocks DHT from doing its thing; rather, it stops DHT from existing in the first place. This explains the more accurate scientific name, 5α-Reductase inhibitors.

This is also why there is so much hype about DHT blockers in the world of hair loss treatment. Many treatments for male pattern baldness only seek to manage the symptoms of the condition. Hair transplants, for example, move healthy hair follicles to different places on your scalp where the follicles are more sensitive to DHT. However, this doesn’t stop further hair loss from occurring.

It’s only DHT blockers that tackle the cause of MPB – DHT production – head on. These will stop hair loss in its tracks.

What’s the Most Effective DHT Blocker Out There?

Of all the different treatments that claim to be DHT blockers, there is only one that can be relied upon. This is known as Finasteride, but it is often sold under the brand name Propecia. According to the science, it is the most effective treatment for MPB on the market.

Finasteride comes in the form of a tablet that is taken daily – and it immediately gets to work to inhibit the work of that enzyme 5α-Reductase. As a result, less DHT will be present in your scalp. According to some studies, we’re talking more than 60% less.

Theoretically, this should be great for your hair – and, in practice, the evidence suggests that it works very effectively too. According to a review of three clinical trials, hair loss was stopped in 90% of men, whilst hair regrowth was seen in 77%. Similarly, a trial into 3,000 men saw a 87% rate of regrowth.

Finasteride works, thanks exclusively to its DHT-blocking potential. However, it is not an immediate fix. Unfortunately, there isn’t one of those for MPB. Whilst it will stop your hair thinning, real results will come with persistent use over six months or more.

Other DHT Blockers?

The internet is full of scams and dodgy vendors seeking to sell things that don’t necessarily work – and medicinal products are no exception.

To avoid disappointment, it is vital that you know what you are buying – and being aware of products that aren’t quite so effective for treating hair loss can be helpful. “Herbal” remedies, including pumpkin seed oil and pygeum bark, while often sold as natural DHT blockers, have not been found by any scientific studies to be effective, for example. The same applies to nettle and green tea too.

There is some evidence, however, that saw palmetto, an extract from a plant native to Florida, may work in blocking 5α-Reductase in a similar way to Finasteride. In one study, for example, treatment with the extract increased hair coverage in 40% of men.

Despite the potential that saw palmetto promises, though, its powers are not certain. If you want as good a chance as possible to block DHT and encourage hair regrowth, there is only one answer – and that’s Finasteride.

How about Minoxidil?

Whilst not a DHT blocker strictly – as it doesn’t intervene in the process of hormone conversion association with 5α-Reductase – there is another option to help keep the hair on your head. That’s Minoxidil, or Regaine. While approved by the FDA as a treatment for MPB, it works in a slightly different way.

Instead of blocking DHT production, Minoxidil cultivates the health of your scalp – and, therefore, your hair follicles. It is a vasodilator, meaning that it widens the blood vessels in your scalp to encourage blood flow to the area. This way, more nutrients and oxygen arrives to the scalp to keep your follicles in good shape.

When combined with a DHT blocker like Finasteride, it works wonders. Combined Finasteride and Minoxidil produces results in 94% of cases, according to studies.

Key Takeaways

DHT blockers – or 5α-Reductase inhibitors, as they are more accurately known – are medicines that prevent your body from producing as much of that male sex hormone, dihydrotestosterone. By reducing the amount of DHT in your system, DHT blockers prevent hair loss – and, in some cases, encourage hair regrowth. While many medicines claim to be DHT blockers, there is only one that is truly effective. That’s Finasteride.


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A. Rossi, E. Mari, M. Scarnò, V. Garelli, C. Maxia, E. Scali, A. Iorio, M. Carlesimo (2012). Comparitive Effectiveness and Finasteride Vs Serenoa Repensscribble-underline in Male Androgenetic Alopecia: A Two-Year Study –


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While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

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