Dutasteride for hair loss in London: stronger than finasteride, and what that actually costs you
Dutasteride suppresses over 90% of serum DHT and outperforms finasteride in head-to-head trials. It also stays in your body for months. Here's the trade in full.
Leila Nassar
Consultant Dermatologist · Hair & Scalp
In short
- Dutasteride inhibits both type I and type II 5-alpha reductase; finasteride only type II. Serum DHT falls by over 90% versus about 70%.
- In head-to-head trials at 0.5mg daily it produced roughly 30% greater hair count improvement than finasteride 1mg at 24 weeks.
- It is licensed in the UK for benign prostatic hyperplasia, not hair loss. All hair use is off-label.
- Its half-life is about five weeks, so it takes roughly six months to clear. Side effects, if they occur, take far longer to resolve than with finasteride.
- Side effect rates are broadly comparable to finasteride in trials but somewhat higher for libido and ejaculatory effects.
- Many London clinicians use 0.5mg twice or three times weekly rather than daily — the long half-life makes intermittent dosing pharmacologically sensible.
- It is a reasonable step for men losing ground on finasteride, not a routine first-line choice.
- Blood donation is prohibited for six months after your last dose.
- Mesotherapy with injectable dutasteride is offered across London; the evidence is far thinner than the marketing suggests.
- Expect £25–£60 a month privately in London including prescriber review.
>90%
Serum DHT suppression
+~30%
Vs finasteride hair count
~5 wks
Elimination half-life
£25–£60
London monthly cost
Dutasteride is the drug men graduate to. Typically the conversation starts like this: three years on finasteride, good early response, and now the crown is quietly giving way again. The options are to accept slow attrition, to add density surgically, or to suppress DHT harder. Dutasteride is the third option, and it works.
It is also the drug that punishes impatience. Where finasteride washes out in days, dutasteride lingers for months. That single pharmacokinetic fact should shape how you start it, how you test it, and how much thought goes in beforehand.
Finasteride is a decision you can reverse in a week. Dutasteride is a decision you live with for half a year.
How much better is it, really
The best evidence comes from randomised comparisons in men with androgenetic alopecia. At 24 weeks, dutasteride 0.5mg daily produced significantly greater increases in target-area hair count and thickness than finasteride 1mg daily, with the largest differences at the vertex. Longer studies from Korean and Japanese cohorts support durability.
The practical translation: dutasteride is meaningfully stronger, not transformationally different. A man with a Norwood 5 pattern does not become a Norwood 2 on it. A man losing ground on finasteride frequently stops losing ground. That is the realistic offer.
Dosing schedules used in London practice
- 0.5mg daily — the trial dose and the most effective schedule. Highest exposure and highest side effect probability.
- 0.5mg three times weekly — very common in London; retains substantial DHT suppression thanks to the long half-life.
- 0.5mg twice weekly — a conservative entry point, frequently used for men switching from finasteride.
- Escalation approach — start twice weekly for eight weeks, review tolerance, then increase if the response is inadequate.
- Topical dutasteride — compounded, increasingly marketed, weakly evidenced. Reasonable to try, unreasonable to pay a premium for.
Side effects and the half-life problem
Reported rates for reduced libido, erectile dysfunction, ejaculatory disorder and gynaecomastia are broadly similar to finasteride, running a little higher in most datasets. What differs is the exit. Stop finasteride and serum DHT normalises within a couple of weeks. Stop dutasteride and you are waiting months for the drug to clear, with symptoms potentially persisting throughout.
This is the argument for starting low and intermittently. It is also the argument for not starting at all if you found finasteride difficult — a drug you tolerated poorly at 70% DHT suppression is unlikely to feel better at 90%.
Monitoring, prescribing and cost in London
- Off-label prescribing means you need a prescriber willing to document the discussion — most London hair clinics and private dermatologists will.
- Baseline: sexual function, mood, and PSA in men over 40. Dutasteride also halves PSA.
- Review at 8–12 weeks for tolerance, at 6 months for early effect, and at 12 months with standardised photographs for the real verdict.
- Cost: generic dutasteride is inexpensive; expect £15–£35 a month for the drug, plus £50–£150 per review consultation.
- Do not donate blood for six months after your last dose — this is a formal UK requirement, not a precaution.
Take this with you
What to ask a London clinic
Copy these into your notes app before any consult. Any specialist worth your money will welcome them.
- 1Why dutasteride for me rather than optimising my current finasteride regimen?
- 2Can we start at twice or three times weekly rather than daily?
- 3Given the five-week half-life, what is your plan if I get side effects?
- 4Will you document baseline sexual function, mood and PSA before I start?
- 5Is the prescription being issued off-label, and is that recorded in my notes?
- 6What price am I paying for the drug versus the pharmacy generic price?
- 7At what point would you tell me to stop and consider surgery instead?
Frequently asked
Common questions
Is dutasteride better than finasteride for hair?+
Yes, measurably. Head-to-head trials show roughly 30% greater hair count improvement at 24 weeks, with the biggest advantage at the vertex. It is stronger, not categorically different.
Is dutasteride licensed for hair loss in the UK?+
No. It is licensed for benign prostatic hyperplasia. Use for androgenetic alopecia is off-label, which is legal and common but should be explicitly discussed and documented.
How long does dutasteride stay in your system?+
Its terminal half-life is around five weeks, meaning roughly five to six months for meaningful clearance after your last dose. This is the single most important difference from finasteride.
Can I switch straight from finasteride to dutasteride?+
Yes, no washout is needed. Many clinicians start at two or three doses a week to gauge tolerance before considering daily dosing.
Are the side effects worse than finasteride?+
Rates in trials are broadly comparable, trending slightly higher for libido and ejaculatory effects. The greater practical concern is duration: anything that develops takes months rather than weeks to resolve.
Does dutasteride cause permanent problems?+
Persistent symptoms after stopping are reported for both 5-alpha reductase inhibitors and remain rare and contested. The longer clearance time makes attribution harder and recovery slower.
Can women take dutasteride?+
Rarely, and only under specialist supervision in postmenopausal women. It is contraindicated in pregnancy and women of childbearing potential should not handle leaking capsules.
Does it affect PSA?+
Yes, it roughly halves PSA readings. Always tell whoever orders prostate testing that you take it.
Is injectable dutasteride mesotherapy worth it?+
London clinics charge £150–£400 a session for it. The published evidence is small-scale and low quality compared with oral dosing. Oral or topical is the better value starting point.
Can I take it with minoxidil?+
Yes, and it is the standard combination. They act on different mechanisms — DHT suppression and growth phase extension — and their effects are additive.
How much does dutasteride cost in London?+
Generic capsules run around £15–£35 a month; with private prescriber reviews budget £25–£60 a month overall. Clinics that bundle it into four-figure packages are charging for convenience, not medicine.
Why can't I donate blood on dutasteride?+
Because the drug is teratogenic and could be transferred to a pregnant recipient. UK blood services require a six-month deferral after your last dose.
Sources & further reading
References
- [1]electronic Medicines Compendium — Dutasteride 0.5mg SmPC
- [2]Gubelin Harcha W et al. — Randomised trial of dutasteride versus finasteride in men with AGA
- [3]NHS Blood and Transplant — medication donor deferral guidance
- [4]British Association of Dermatologists — male pattern hair loss patient information
Reviewed by
Leila Nassar
Consultant Dermatologist · Hair & Scalp
Leila Nassar MRCP(Derm) is a consultant dermatologist with a subspecialty interest in hair and scalp disease at a large London teaching hospital. She runs a weekly cicatricial alopecia clinic and lectures nationally on medical management of hair loss.
Keep reading
Related, trichologist-reviewed
Treatments
Finasteride side effects: an honest London risk assessment, not a scare story and not a sales pitch
Finasteride is either a miracle or a menace depending on which forum you read. The clinical reality sits in between, and the numbers are knowable.
Read
Treatments
Topical dutasteride in London — stronger than finasteride, applied to the scalp
Topical dutasteride is compounded, unlicensed, and quietly one of the most effective hair-loss treatments available in London.
Read
Hair loss
Minoxidil vs finasteride: the London 2026 evidence-based guide
Minoxidil grows hair. Finasteride stops loss. Confusing them is the most common mistake in male-pattern hair loss. Here is the London 2026 evidence-based framework.
Read