Finasteride and dutasteride for hair loss

Finasteride and dutasteride are the two oral treatments that work by lowering DHT, the hormone behind pattern hair loss. They are the most effective medical option for keeping hair in men, and understanding how they work helps you weigh them up.

This article explains what they do, how they differ, and the practical points that come up before starting.

How they work

Both drugs block the enzyme 5-alpha-reductase, which converts testosterone into DHT. Less DHT reaching the follicle means less of the miniaturisation that drives pattern hair loss, which lets follicles recover some of their lost size and protects those still working.

They act on the cause of pattern hair loss rather than masking it, which is why they are the backbone of medical treatment for men.

Finasteride

Finasteride at 1mg daily is the most evidence-based treatment for male pattern hair loss and is licensed for that use. It blocks one of the two forms of the enzyme and lowers scalp DHT substantially.

In studies it slows or stops hair loss in around nine in ten men and produces some regrowth in around six in ten over twelve months. It is taken as a single small daily tablet, and like all of these treatments it works only while you continue it.

Dutasteride

Dutasteride at 0.5mg daily blocks both forms of 5-alpha-reductase, so it lowers DHT more completely than finasteride does. It is well evidenced for hair loss and is licensed for it in some countries, though in the UK it is prescribed off-label for this purpose, meaning it is used outside its UK licence on the basis of good evidence and clinical judgement.

It tends to be chosen where finasteride has not given enough benefit, or by men who have read about both and want the more potent option from the start. It also stays in the body longer than finasteride, which is a relevant point for anyone who might want to stop it cleanly, and an important one for the pregnancy considerations covered in a separate article.

What to expect once you start

Give it time. Visible change usually takes three to six months to begin and is best judged at twelve months. A short-lived increase in shedding early on can happen and is not a reason to stop.

Practically, they are easy to take: one small tablet a day, with or without food, and a missed dose now and then will not undo your progress. The thing that matters is steady use month after month rather than getting every single day perfect.

These tablets are often combined with topical minoxidil, which works by a different mechanism, because the two together outperform either alone. We cover that combination, and treatment for women, in its own article.

Practical points before starting

A few things are worth knowing up front:

• Finasteride lowers the PSA blood test used in prostate cancer screening by roughly half. It does not hide cancer, but any doctor interpreting a future PSA needs to know you take it, so they can adjust for it.

• Sexual side effects affect a small minority of men and are covered honestly in a dedicated article, along with the unsettled question of persistent symptoms after stopping.

• These medicines are not prescribed to women who are pregnant, may become pregnant, or are planning pregnancy within the next twelve months, for reasons explained in the pregnancy article.

• Benefit depends on consistency, so they suit people ready to take a daily tablet for the long term.

This may not be right for you if

An oral DHT-blocker may not be the right path if you would prefer to avoid any systemic hormonal effect, in which case topical minoxidil alone is an option, or if you have specific concerns about the side effects that outweigh the benefit for you. The assessment is there to talk these through, not to talk you into anything.

The honest summary

Finasteride and dutasteride lower DHT and are the most effective tablets for holding and partly reversing male pattern hair loss, with dutasteride the more potent and longer-acting of the two. Both reward patience and consistency. A short assessment with one of our doctors will go through whether they suit you and which makes sense for your pattern.

Ready to start?

If you want to move from reading to acting, the next step is a short, confidential assessment with one of our doctors.

Begin your assessment at this link. Online or in person at Westfield London.