Ask any UK online pharmacy team what the three most-asked hair-loss treatments are and you get the same list every time: finasteride, minoxidil and dutasteride. All three appear repeatedly in patient questions, all three do genuinely help many men with pattern hair loss, and yet they work in different ways, have different licensing status and are matched to different clinical situations.
This guide compares them in plain English — mechanism, dose, response timeline, side effects and how UK clinicians typically pair or sequence them.
The three treatments at a glance
The table below summarises the differences a UK clinician weighs in a hair-loss consultation.
| Treatment | Route & dose | Mechanism | UK licensing for hair loss | Typical response window | Main side-effect concerns |
|---|---|---|---|---|---|
| Finasteride | Oral, 1 mg once daily | Inhibits 5α-reductase type II — reduces DHT | Licensed for male-pattern hair loss | Reduced shedding at 3 months; visible response at 6 months; peak at 12 months | Sexual side effects in a minority; mood effects |
| Minoxidil (topical) | Topical 2% or 5%, applied to scalp once or twice daily | Opens potassium channels; prolongs the anagen (growth) phase | Licensed for pattern hair loss (male and female strengths) | Reduced shedding at 8–12 weeks; regrowth at 4–6 months | Scalp dryness/itch; initial shedding; unwanted facial hair (uncommon) |
| Dutasteride | Oral, usually 0.5 mg daily | Inhibits 5α-reductase type I and II — reduces DHT more fully | Not UK-licensed for hair loss (licensed for BPH); off-licence use only | Similar to finasteride; potentially slightly greater average regrowth | Similar to finasteride; longer half-life, so effects and side effects persist longer |
Finasteride — how it works, dose and response timeline
Male-pattern hair loss is driven by the sensitivity of scalp hair follicles to dihydrotestosterone (DHT), a potent androgen made from testosterone by the enzyme 5α-reductase. Over years, DHT causes follicle miniaturisation — the visible thinning at the crown and hairline. Finasteride is a selective inhibitor of 5α-reductase type II, the isoform predominant in scalp and prostate tissue. At 1 mg daily it reduces scalp DHT by roughly two-thirds, which is usually enough to slow, halt or partially reverse miniaturisation for responders.
The UK-licensed dose for male-pattern hair loss is 1 mg oral, once daily. Higher doses (5 mg) are licensed for benign prostatic hyperplasia and do not produce proportionally more hair regrowth — we cover this in more detail in how much finasteride to take for hair loss. Realistic milestones: reduced shedding around 3 months, visible response for responders around 6 months, and peak response around 12 months.
Minoxidil — how it works, topical vs oral off-licence
Topical minoxidil was originally developed as an oral antihypertensive; the hair-growth effect was noticed as a side effect and led to the topical formulation. On the scalp it acts as a potassium-channel opener and prolongs the anagen (growth) phase of the hair cycle, giving existing follicles a longer active phase before shedding. The exact molecular pathway is not fully understood — that is not unusual for older topical dermatology drugs — but the clinical effect is well-documented.
Topical strengths in the UK are 2% (typically used for female-pattern hair loss) and 5% (used for male-pattern hair loss and, sometimes, for women under clinician supervision). Formulations include solutions and foams. Application is once or twice daily to the affected areas of the scalp, and consistency matters more than technique. Some UK clinicians also prescribe low-dose oral minoxidil off-licence for pattern hair loss, where topical application is not tolerated or convenient.
Common practical issues are scalp dryness or itch (more common with alcohol-containing solutions than foam), a mild initial shed in the first weeks of use, and — rarely — unwanted facial hair growth if the product transfers from scalp to face. Stopping minoxidil generally leads to gradual loss of the gains over several months, so it is used long-term.
Dutasteride — how it works and why it is not UK-licensed for hair loss
Dutasteride is a dual inhibitor: it blocks both 5α-reductase type I and type II. This results in more complete DHT suppression — around 90% in some studies — compared with finasteride's suppression via type II alone. Trials directly comparing dutasteride and finasteride for hair loss have generally shown slightly greater regrowth with dutasteride, particularly at higher doses.
In the UK, dutasteride is licensed for benign prostatic hyperplasia (prostate enlargement), not for hair loss. Some UK clinicians will prescribe it off-licence for pattern hair loss — typically at 0.5 mg daily — when a patient has not responded adequately to finasteride, when side effects on finasteride have been an issue but dutasteride is being trialled at the patient's informed choice, or when the pattern is more advanced. Off-licence prescribing requires a clear conversation about evidence, risks and monitoring.
Two additional practical points about dutasteride matter: it has a much longer half-life than finasteride (weeks rather than hours), so any beneficial effect — and any side effect — takes longer to appear and longer to reverse on stopping. And because it is used off-licence for hair loss, it is not typically an NHS-funded option for this indication.
Combining treatments — when it makes sense
Because finasteride/dutasteride and minoxidil target different parts of the problem — DHT-driven miniaturisation on one side, growth-phase length on the other — they can produce additive results when combined. The most common UK regimen for progressed male-pattern hair loss is oral finasteride 1 mg daily plus topical minoxidil, and studies show this combination outperforms either treatment used alone on average.
Dutasteride is not usually stacked with finasteride (they act on the same enzyme family) but is sometimes used instead of finasteride, alongside minoxidil, for patients where a stronger DHT suppression is being considered. Sequencing is also common: starting with finasteride plus minoxidil, reviewing at 6–12 months and considering dutasteride only if response has been inadequate.
Side effects compared
All three treatments have generally acceptable safety profiles at licensed doses, but the profiles differ:
- Finasteride: a minority of men report reduced libido, erectile changes or ejaculation changes. Mood effects have been reported, and — rarely — breast tenderness or enlargement. Most reversible side effects resolve on stopping.
- Minoxidil (topical): scalp dryness, itch or mild dermatitis, initial shedding, occasional unwanted facial hair from transfer. Rarely, low-dose oral minoxidil can cause dose-related fluid retention or a change in resting heart rate — one reason it is prescribed with clinician supervision.
- Dutasteride: side-effect profile broadly overlaps with finasteride but effects — beneficial and adverse — last longer given the extended half-life. Off-licence status means less UK-specific safety data than for finasteride.
For related reading on the interaction between hormone changes and hair, see does low testosterone cause hair loss?, which addresses a common confusion about testosterone and pattern hair loss.
How UK clinicians match a patient to a treatment
A Farmeci hair-loss consultation typically covers the pattern and rate of your hair loss, your age, family history, general health and medications, side-effect tolerance, and how important different aspects (efficacy, side-effect risk, licensing status, ongoing monitoring) are to you. The rough shape of a UK-typical approach:
- Early or moderate pattern hair loss: topical minoxidil alone, or finasteride 1 mg alone, depending on preference.
- Established pattern hair loss: oral finasteride 1 mg plus topical minoxidil.
- Progressed pattern hair loss or inadequate response after 12 months: discussion of dutasteride off-licence, with clear explanation of licensing status and risks.
- Women with female-pattern hair loss: topical minoxidil (with strength decided in consultation). Systemic 5α-reductase inhibitors are avoided due to teratogenicity risk.
The Skin & Hair section covers adjacent topics — dermatology treatments, acne and other scalp conditions — that sometimes overlap with pattern hair loss assessment. And whether treatment is right for you, and which combination, is always a clinician-led decision, not a self-select choice.