Comparison
Finasteride vs Dutasteride
Both drugs block the enzyme that produces DHT, the hormone driving male pattern hair loss — but dutasteride blocks more of it. That makes it more powerful and, for some, riskier. Here's how they actually compare.
| Finasteride | Dutasteride | |
|---|---|---|
| Enzyme blocked | 5-alpha-reductase type II only | Types I and II — broader suppression |
| Scalp DHT reduction | ~65–70% | ~90% |
| Approval for hair loss | FDA-approved (men) | Off-label in most countries (approved in South Korea/Japan) |
| Regrowth | ~65% see improvement | Superior to finasteride in head-to-head trials (Olsen 2006) |
| Half-life | ~6–8 hours | ~5 weeks (stays in the body far longer) |
| Side-effect profile | ~2% sexual side effects | Similar type, slightly higher rates |
| Typical UK cost | £10–20/month | £25–60/month |
| Best for | First-line for most men | Those who plateau on finasteride |
The verdict
Finasteride is the sensible first choice — well-studied, approved, cheaper. Dutasteride is the escalation: stronger DHT suppression and better regrowth for men who don't respond adequately to finasteride, at the cost of a longer half-life and a slightly higher side-effect rate. Many specialists switch patients to dutasteride only after finasteride plateaus.
Frequently asked questions
Is dutasteride better than finasteride for hair loss?
In head-to-head trials dutasteride produced more regrowth, because it suppresses scalp DHT by ~90% versus finasteride's ~65%. However it's used off-label for hair loss in most countries and has a longer half-life, so finasteride is usually tried first.
Can you switch from finasteride to dutasteride?
Yes — many hair-loss specialists move patients to dutasteride when finasteride stops delivering results (a plateau). This should be done under medical supervision.
Why is dutasteride's long half-life important?
Dutasteride stays in the body for about 5 weeks versus finasteride's several hours. This means more sustained DHT suppression, but also that any side effects take longer to clear after stopping.
Related reading: full research article →
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Informational only, not medical advice. Costs and side-effect rates vary by individual and prescriber. Always consult a qualified clinician before starting or changing treatment.