If you're researching hair loss treatment in New Zealand, two drug names dominate the conversation: finasteride and dutasteride. Both are prescription-only. Both work — but they work differently, and which one is right for you depends on how aggressive your hair loss is, how you respond to side effects, and, in New Zealand, on the fact that dutasteride is not an approved medicine here, which puts the two on a very different legal footing.
This is a practical, NZ-specific comparison written by a doctor.
How they both work (the 30-second version)
Male pattern hair loss is driven by DHT (dihydrotestosterone) binding to hair follicles in genetically susceptible scalp areas, causing follicle miniaturisation and eventually loss. The enzyme that converts testosterone into DHT is 5-alpha reductase, and it comes in two flavours:
- Type 1 — found in skin and sebaceous glands
- Type 2 — dominant in scalp follicles, prostate, liver
| Drug | What it blocks | DHT reduction (scalp) |
|---|---|---|
| Finasteride | Type 2 only | ~70% |
| Dutasteride | Type 1 + Type 2 | ~90% |
More DHT suppression = more hair preserved or regrown. That's the headline trade-off.
What does each one do for hair?
Finasteride (1 mg daily)
The most-studied hair loss drug in history. In long-term studies of men with mild-to-moderate male pattern hair loss:
- ~85–90% of men stop further hair loss
- ~65% see visible regrowth at 12 months
- Effects plateau around 24 months and are maintained as long as you keep taking it
In NZ, finasteride 1 mg is Medsafe-registered specifically for male pattern hair loss. The PROPECIA data sheet states it is "indicated for the treatment of men with male pattern hair loss (androgenetic alopecia) to increase hair growth and prevent further hair loss". It is not indicated for women or children. (The separate 5 mg product is the one registered for benign prostatic hyperplasia — same molecule, different dose and different registered use.)
Dutasteride (0.5 mg daily)
In head-to-head trials, dutasteride produces more hair density, more terminal hairs, and faster results than finasteride — particularly in men with aggressive or vertex-dominant loss. It's not a magic bullet, but the regrowth tends to be visibly better.
In NZ, dutasteride is currently not an approved medicine at all — Medsafe publishes no data sheet for any dutasteride product, and the NZ Formulary lists it as an unapproved medicine. That puts it on a very different footing from finasteride 1 mg, which is registered here specifically for this use. See Access in NZ below.
Side effects — the part everyone wants to know
The side-effect profile is similar between the two drugs, with dutasteride generally producing them at slightly higher rates because of stronger DHT suppression.
| Side effect | Approx. rate (finasteride) | Approx. rate (dutasteride) |
|---|---|---|
| Reduced libido | ~2–4% | ~3–5% |
| Erectile dysfunction | ~1–3% | ~2–4% |
| Reduced ejaculate volume | ~1–2% | ~2–3% |
| Mood changes | <1% | <1–2% |
| Gynaecomastia (breast tissue) | <1% | <1–2% |
A few honest realities:
- Most men experience no sexual side effects. The men who do usually notice within the first 2–3 months.
- Side effects usually reverse on stopping the drug — but not always. The NZ Propecia data sheet records post-marketing reports of decreased libido and sexual dysfunction that continued after treatment was stopped, alongside depression and suicidal ideation. These reports are voluntary, so the true frequency isn't known and causation isn't established — but "it all goes away when you stop" overstates what the evidence supports. Worth knowing before you start, not after.
- Side effects are dose-related. Some men who don't tolerate daily 1 mg finasteride do fine on 0.5 mg every other day, or on topical formulations.
Topical formulations — what they change, and what they don't
There is no registered topical finasteride product in New Zealand. The NZ Formulary lists finasteride as an oral tablet only, and no topical preparation has been assessed by Medsafe for quality, safety or efficacy. That matters for how you read the claims made for topical finasteride online, because the usual selling point — the drug's effect without the drug's systemic exposure — is not what the pharmacology shows.
- Finasteride blood levels are much lower. In a randomised trial of 458 men (Piraccini et al., Journal of the European Academy of Dermatology and Venereology, 2022, doi:10.1111/jdv.17738; funded by Almirall, which developed the spray studied), peak plasma finasteride was more than 100 times lower with a metered topical spray than with the 1 mg tablet.
- Systemic exposure is reduced, not removed. In that same trial, serum DHT still fell by 34.5% on the topical, against 55.6% on the tablet. Finasteride is absorbed through the scalp — so "the efficacy of the drug without the systemic exposure" overstates what the topical route does.
- How much gets into you depends on how much goes on. Applied volume and frequency drive systemic exposure more than the word "topical" does. In dose-ranging work on a 0.25% solution (Caserini et al., International Journal of Clinical Pharmacology and Therapeutics, 2016, doi:10.5414/CP202467), 100–200 µL a day reduced serum DHT by roughly a quarter, while larger volumes — and, in an earlier study by the same group, twice-daily use — suppressed it about as much as the tablet did. A preparation that cannot be metered accurately will not reliably deliver the dose that was studied.
- Fewer side effects is a reasonable expectation, not a proven one. Much lower drug exposure is a sound reason to expect a gentler side-effect profile. But no trial has been designed to test whether topical causes fewer sexual side effects than oral, so this sits as a likelihood rather than a settled fact.
Strength, vehicle and metering vary between preparations too, so the dose that was studied is not necessarily the dose that gets delivered.
Access in NZ
Neither drug is funded by Pharmac for hair loss, and the two sit very differently in New Zealand's medicines rules:
- Finasteride — Medsafe-registered, with the 1 mg tablet registered specifically for male pattern hair loss in men. The only subsidised form is the 5 mg tablet used for prostate enlargement, and only on Special Authority (SA0928). The 1 mg hair-loss tablet is not subsidised.
- Dutasteride — currently not an approved medicine in New Zealand, and not funded. Medsafe currently publishes no data sheet for any dutasteride product, and the NZ Formulary lists it as an unapproved medicine, so no dutasteride product currently holds Medsafe consent to be marketed here (status checked September 2026). There is also no subsidised dutasteride product: it does not appear in the Pharmaceutical Schedule, in either the community section or Section H, the Hospital Medicines List, and in March 2021 Pharmac declined a long-inactive funding application for dutasteride in benign prostatic hyperplasia.
A finasteride 1 mg script is filled at any community pharmacy on the standard NZ private pathway.
How prescribers approach the choice
There's no single right answer, and it isn't a choice to make from an article. In general terms, a prescriber weighs:
- How much DHT suppression the situation calls for, against how much side-effect risk you're prepared to carry.
- Registration status. Only finasteride 1 mg is registered in New Zealand for male pattern hair loss in men. Dutasteride is currently not an approved medicine here at all, which puts it on a different footing entirely.
- Route. Oral and topical formulations differ in systemic exposure — see the topical section above for what that does and doesn't change.
- Whether a second agent is added, which changes both the expected benefit and what has to be monitored.
Your own GP or an NZ telehealth doctor can work through which of these, if any, fits your pattern of loss, your history and your own risk tolerance.
How finasteride is prescribed in NZ
- Book a hair loss consultation with a NZ-registered doctor — your GP, a private telehealth clinic, or a dermatology service
- Confirm pattern of loss, family history, baseline health
- Get a prescription, filled at your nominated pharmacy
- Review at 6 months: photos, side effects, dose adjustment if needed
What about hair transplant?
Medicines act on the hair you still have. A transplant moves hair from areas not affected by DHT (the back and sides of the head) to thinning areas, and does nothing to stop loss elsewhere. Whether either suits you depends on your pattern of loss, and is worth working through with your own doctor. How the surgery itself works is covered in how a hair transplant works in NZ.
Getting this assessed in NZ
Which of these suits you — if either does — depends on your pattern of loss, your history and what else might be contributing, which is a conversation rather than a lookup. Your own GP or an NZ telehealth doctor can assess it.
FAQ
Is dutasteride stronger than finasteride? Yes. Dutasteride suppresses scalp DHT by ~90% vs ~70% for finasteride, producing greater hair density in head-to-head trials.
Does finasteride or dutasteride cause permanent side effects? Side effects usually reverse after stopping, but the NZ Propecia data sheet does record post-marketing reports of decreased libido and sexual dysfunction continuing after treatment was stopped, plus depression and suicidal ideation. Those reports are voluntary, so frequency and causation aren't established — but they're real entries on the data sheet, not internet folklore. Raise any mood change with your doctor promptly.
Is finasteride safe to take long-term? Long-term data extends past 10 years for finasteride 1 mg and it is widely used for indefinite treatment under monitoring. Male breast cancer has been reported post-marketing — report any breast lump, pain or nipple discharge to a doctor promptly.
Can I get finasteride without seeing a doctor in NZ? No. Finasteride 1 mg is a prescription medicine — a NZ-registered doctor has to assess you and prescribe it.
Will I need to keep taking it forever? To maintain results, yes. Stopping causes a return to baseline genetic hair loss within 6–12 months.