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, for dutasteride, your comfort with an off-label prescription.
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 registered for prostate enlargement (Avodart, generics) and is prescribed off-label for hair loss — well-established practice internationally, but off-label here, unlike finasteride 1 mg.
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 — a useful middle ground
Topical finasteride (and increasingly topical dutasteride) is compounded by some NZ pharmacies. Applied to the scalp, blood levels are far lower than oral, which reduces systemic side effects significantly while preserving most of the scalp DHT suppression.
This is a great option if:
- You're getting (or worried about) sexual side effects
- You want the efficacy of the drug without systemic exposure
- You're a younger man planning a family in the next few years
The catch: topical compounded medication is unfunded and prepared by a compounding pharmacy on a per-prescription basis.
Access in NZ
Oral finasteride and dutasteride at hair-loss doses are unfunded by Pharmac for hair loss (the funded indication is BPH) — you fill the script at any community pharmacy at the pharmacy's private rate, which is generally modest for the oral generics. Topical compounded formulations are prepared by compounding pharmacies (Compound House, Optimus and others) and dispensed against a doctor's prescription.
Which should you actually choose?
A reasonable algorithm:
- Mild-to-moderate hair loss, no major risk factors → start with finasteride 1 mg daily. It's well-studied, cheap, and most men do well on it.
- Aggressive loss, vertex-dominant pattern, or finasteride didn't work after 12 months → step up to dutasteride.
- Concerned about systemic side effects, or planning fertility within 2 years → start with topical finasteride (or topical dutasteride for stronger effect).
- Anyone → add minoxidil 5% topical. It works through a different mechanism and the combination outperforms either alone.
How to get either prescribed online 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 — picked up at your nominated pharmacy or compounded for topical
- Review at 6 months: photos, side effects, dose adjustment if needed
What about hair transplant?
Drugs preserve and grow what's there. Transplants move hair from areas not affected by DHT (back of the head) to thinning areas. They're complementary — most men who get a transplant should also be on finasteride or dutasteride to preserve the non-transplanted hair. Dr Jack Yeoman performs hair transplant surgery in New Zealand at Gro Clinics, Auckland.
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. Enhanced Men runs a telehealth hair loss assessment: a 30-minute consultation with an NZ-registered doctor covering what's driving your hair loss and the medical options for 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.
Can you switch from finasteride to dutasteride? Yes — many men do, especially after 12 months of finasteride if regrowth has plateaued.
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 or dutasteride without seeing a doctor in NZ? No. Both are prescription-only in NZ. You need a NZ-registered doctor to prescribe — most online consults take under 15 minutes.
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.