Topical dutasteride for hair loss: How it works, side effects to know, and how to access it in the UK

If you’ve tried dutasteride or finasteride tablets and didn’t love the side effects, or you’re starting out and want something that acts mainly at the scalp, a topical option may appeal.

A new 2025 study has put topical dutasteride in the spotlight, showing strong results with lower impact on the rest of the body.

Below, we cover how topical dutasteride works, what the latest evidence shows, how it compares with oral dutasteride and finasteride, and how to access it safely in the UK.

What is topical dutasteride?

Dutasteride is in the same family as finasteride. Both are 5-alpha-reductase (5-AR) inhibitors, which block the enzyme that converts testosterone into dihydrotestosterone (DHT). High DHT in the scalp shrinks hair follicles over time, so hairs become shorter, thinner, and fewer. Lowering DHT helps break that cycle.

Although they work in similar ways, there is an important difference.

• Finasteride mainly blocks type II 5-AR.
• Dutasteride blocks both type I and II, leading to greater DHT suppression overall.

Dutasteride is available as oral tablets, but in the UK it can also be compounded into a topical solution or spray by specialist pharmacies. Applied directly to thinning areas, it aims to act strongly at the scalp while reducing whole-body exposure and potential side effects.

Does topical dutasteride work?

Yes - and the latest research backs it up.

A 2025 “phase 2” study tested three topical dutasteride strengths (0.01%, 0.02%, 0.05%) against placebo and 1 mg oral finasteride in men with male-pattern baldness over 24 weeks. The 0.05% dutasteride solution performed best, delivering:

• The largest increases in target-area hair count.
• Higher patient-reported improvements than oral finasteride (93.1% vs. 71.4% at week 24).

Importantly, topical dutasteride caused smaller shifts in blood hormone levels than oral tablets, suggesting less systemic absorption and possibly fewer whole-body side effects.

Phase 3 trials (the final stage before a medicine can be submitted to the regulator for approval) are now in progress. But so far the signs are clear: topical dutasteride could be a strong option for men seeking results without committing to oral therapy.

Who should and shouldn’t use topical dutasteride?

Good candidates for topical dutasteride

• Men over 18 with male pattern baldness who want a topical option.
• Men who had side effects on oral finasteride or oral dutasteride.
• Men in the early to moderate Norwood stages where miniaturised hairs are still present.
• Men willing to apply the product consistently every day for at least 3 to 6 months.

Who should avoid topical dutasteride?

• Women and children
• Anyone with a known sensitivity to finasteride, dutasteride, other 5-alpha-reductase inhibitors, or any ingredient in the formulation.
• Men who are already using another DHT-blocking treatment. Do not combine finasteride and dutasteride - oral or topical, unless a clinician specifically advises and monitors it.
• People with liver failure.

Topical dutasteride vs oral dutasteride

No trials have directly compared the two just yet. But we know:

• Oral dutasteride works systemically, lowering DHT across the body. This makes it highly effective but also more likely to cause side effects.
• Topical dutasteride targets the scalp and shows strong efficacy, even outperforming oral finasteride in the new study. Side effects are usually milder and limited to scalp irritation, though systemic effects remain possible.

Both options work gradually because hair grows in slow cycles, so results take time, and while some people may notice changes sooner with oral treatment, results vary from person to person.

Dutasteride vs finasteride

Both dutasteride and finasteride inhibit the enzyme 5-alpha-reductase (5AR), which converts testosterone into dihydrotestosterone (DHT). DHT drives male pattern hair loss by miniaturising hair follicles.

Both medicines are available as oral tablets or capsules, and there are topical formulations that are applied directly to the scalp. Either route can be paired with minoxidil, a growth stimulator that increases blood flow to follicles and often acts like a hair “fertiliser.”

How they work

• Finasteride blocks type II 5AR.
• Dutasteride blocks type I and type II 5AR, so it suppresses DHT more broadly.
• Research suggests dutasteride is about three times more potent than finasteride at inhibiting type II 5AR, and about 100 times more potent at inhibiting type I 5AR.

How they compare in studies

• Oral dutasteride has shown stronger hair-count gains than oral finasteride in trials, which fits with its greater DHT suppression.
• Potency can come with trade-offs. Because oral dutasteride acts systemically and lowers DHT more, side effects can be more common than with oral finasteride, although many men still tolerate treatment well.

Topical options focus action at the scalp. At the highest strength, topical dutasteride has outperformed oral finasteride at 24 weeks in the same dataset, while producing smaller changes in blood hormones. This makes topical a compelling choice for men who want strong results with lower whole-body exposure.

Is topical dutasteride available in the UK?

Topical dutasteride is only available as an unlicensed, compounded preparation. To ensure safety, use a GPhC-registered pharmacy or regulated online clinic with a UK prescriber.

Finasteride and dutasteride are not usually available on the NHS for hair loss, but can be prescribed privately after assessment.

At Voy, we currently offer oral capsules combining dutasteride with minoxidil, or finasteride with minoxidil. We don’t offer topical dutasteride yet, but are reviewing the new evidence carefully.

Topical dutasteride and minoxidil

Minoxidil (which you might know as Regaine in the UK) boosts blood flow to follicles, helping them grow thicker hairs. It doesn’t block DHT, so it’s often combined with dutasteride or finasteride.

Evidence shows that combining minoxidil with dutasteride is more powerful:

• In one 24-week study, dutasteride plus oral minoxidil produced ~60% greater hair gains than dutasteride alone.
• Together, DHT-blockers protect follicles while minoxidil stimulates new growth, typically delivering fuller results than either on its own.

If you’re weighing up other hair loss medicines, our guide to Finasteride vs Minoxidil explains how these two treatments work and which may be best for you.

Get your hair back

Topical dutasteride could be a strong alternative for men who want effective hair loss treatment with less systemic exposure. But it could be a while before it’s widely available in the UK. In the meantime, there are other effective treatments for male pattern baldness.