Dutasteride

What is Dutasteride?

Dutasteride 0.5mg capsules are a 5-alpha-reductase inhibitor – a type of medicine that lowers levels of dihydrotestosterone (DHT), the hormone that drives male pattern hair loss. It is sold under the brand name Avodart and also as a generic.

How does Dutasteride work?

Dutasteride is a dual 5-alpha-reductase inhibitor: it blocks both the Type I and Type II forms of the enzyme that converts testosterone into DHT, reducing scalp DHT by around 90%.

DHT is an androgen (male hormone) that gradually shrinks genetically sensitive hair follicles, so hairs grow back thinner and shorter until they stop surfacing altogether – the process behind male pattern baldness. By lowering DHT, dutasteride helps protect follicles from further miniaturisation and gives them a chance to recover.

The dual action blocks only the Type II enzyme and reduces DHT by around 70%. Benefits are most visible on the crown and mid-scalp; the frontal hairline responds more slowly to treatment, and results vary from person to person.

Is Dutasteride right for me?

Dutasteride is generally considered for adult men (18+) with male pattern hair loss, particularly those who have seen limited benefit from finasteride or experienced side effects with it. It is not suitable for women, anyone who is or may become pregnant, or people with severe liver problems – this is a safety requirement.

If dutasteride isn’t right for you, our clinicians can suggest alternatives, so it’s best not to rule yourself out before starting. The online assessment is free, takes a few minutes, and is reviewed by a UK prescriber who will confirm what’s suitable for you.

Does Dutasteride work?

Yes – clinical evidence supports dutasteride’s effectiveness for male pattern hair loss, particularly at the crown and mid-scalp. Studies show that most men experience reduced hair loss, and a meaningful proportion see visible regrowth after several months of consistent daily use.

In a randomised trial, dutasteride 0.5mg increased hair count more than finasteride 1mg and placebo over 24 weeks. Results can often be enhanced by combining dutasteride with topical or oral minoxidil, which stimulates growth through a different mechanism — something a prescriber can advise on.

Results vary between individuals, the frontal hairline is less responsive than the crown, and the medicine needs to be taken consistently over the long term. Benefits are maintained only while treatment continues.

Dutasteride vs Finasteride: comparison

Dutasteride and finasteride are both 5-alpha-reductase inhibitors that lower DHT, but they aren’t identical. The key difference is that dutasteride blocks both Type I and Type II enzymes, while finasteride blocks only Type II.

In practice, this means a greater reduction in DHT with dutasteride (around 90% versus around 70%). The table below summarises how they compare.

Because finasteride carries a hair-loss licence, it is usually the first-line choice. Dutasteride may be considered off-label when finasteride hasn’t delivered enough benefit or wasn’t tolerated. The right option depends on your history and goals — which is exactly what the consultation is designed to establish

How long does Dutasteride take to work?

Most men notice early changes – reduced shedding or stabilisation – within 3 to 6 months, with visible thickening typically emerging around 9 to 12 months. A simple guide to what to expect:

• Months 1–3: often no visible change; some men see a temporary increase in shedding as follicles reset. This is a normal early sign the medicine is working.
• Months 3–6: shedding usually slows and hair loss stabilises.
• Months 6–12: visible thickening and regrowth become more apparent, mainly at the crown and mid-scalp.
• 12–24 months: maximum benefit, which can continue improving for up to two years with continued use.

Early months may feel like maintenance rather than growth – that’s expected. If you stop treatment, DHT returns and hair loss typically resumes within 6 to 12 months.

Early months may feel like maintenance rather than growth – that’s expected. If you stop treatment, DHT returns and hair loss typically resumes within 6 to 12 months.

How to take Dutasteride

Take one 0.5mg capsule once daily, with or without food, ideally at the same time each day for consistency. Swallow the capsule whole – do not chew, crush or open it, as contact with the contents can irritate the mouth and throat.

If you miss a dose, don’t double up; simply take your next dose at the usual time. Consistency is key: the benefits are gradually lost if treatment stops.

Who cannot use Dutasteride

Dutasteride isn’t appropriate for everyone, and your consultation will confirm suitability. It should not be used if any of the following apply:

• Women, and anyone who is pregnant or may become pregnant – including handling the capsules, as dutasteride can be absorbed through the skin and may harm a male foetus.
• Known allergy to dutasteride or to soya/peanut – some capsules contain soya lecithin, so check the leaflet for your supplied product.
• Severe liver problems.
• Severe bladder or urinary conditions (discuss with a clinician).
• Men trying to conceive – dutasteride can affect fertility and semen; discuss with your clinician first.

You should also not donate blood while taking dutasteride and for 6 months after your last dose, to avoid a pregnant recipient being exposed to the medicine.

Dutasteride side effects

Most men tolerate dutasteride well, but side effects do occur. The most commonly reported are sexual:

• Reduced libido
• Erectile difficulties
• Changes in ejaculation
• Tender breast tissue (gynaecomastia)

These are often mild and may ease over time. In a small number of men, some sexual side effects have been reported to continue after stopping treatment. Always report breast lumps, pain, enlargement or nipple discharge to a clinician promptly.

Dutasteride and mental health

In May 2026, the MHRA strengthened its safety guidance for finasteride and dutasteride. As a precaution, dutasteride’s product information is being updated to note that mood alterations — including low mood and depression — have been reported with finasteride, a medicine in the same class. If you experience low mood, depression, or any thoughts of self-harm while taking dutasteride, stop and contact your prescriber or a healthcare professional as soon as possible.

If you need urgent support: contact the Samaritans free on 116 123 at any time, call NHS 111 for urgent advice, or call 999 in an emergency.

Dutasteride can also lower PSA (prostate-specific antigen) blood-test levels by about half; if you have a PSA test, tell your doctor you take dutasteride so the result can be interpreted correctly. You can report any suspected side effect through the MHRA Yellow Card Scheme. Always read the patient information leaflet supplied with your medicine.

Alternatives to Dutasteride

If dutasteride isn’t suitable or preferred, there are other effective, prescriber-reviewed hair loss treatments available:

• Finasteride 1mg — the only oral treatment licensed in the UK for male pattern hair loss; blocks Type II 5-alpha-reductase.
• Minoxidil topical solution (Regaine) — applied directly to the scalp to stimulate growth; available over the counter.
• Oral Minoxidil — a low-dose daily tablet, by prescription.
• Hair Loss Dual Action — combination products that pair a DHT blocker with minoxidil for a two-pronged approach.