How each one works
Finasteride is a 5-alpha reductase inhibitor: it blocks the conversion of testosterone into dihydrotestosterone (DHT), the hormone most strongly linked to male pattern hair loss. It is licensed in the UK for “treatment of men with male pattern hair loss (androgenetic alopecia) to increase hair growth and prevent further hair loss,” at a dose of 1mg once daily, with continuous use for 3 to 6 months needed before benefit is typically seen.
Minoxidil’s exact mechanism for hair growth is not fully understood; it is thought to widen blood vessels and shorten the resting phase of the hair growth cycle, encouraging follicles into active growth sooner. Topical minoxidil (2% or 5%, foam or solution) is licensed for use without a prescription in the UK. Oral minoxidil, by contrast, is licensed in the UK only for severe, treatment-resistant high blood pressure; using it for hair loss means using it off-label, at a much lower dose than its licensed blood-pressure use, and only available through a private prescriber.
Regulatory status: the key practical difference
| Finasteride 1mg | Topical minoxidil | Oral minoxidil | |
|---|---|---|---|
| UK status | Prescription-only medicine | Available without prescription (pharmacy medicine) | Prescription-only, and off-label for hair loss |
| How you get it | Private prescriber consultation | Buy directly from a pharmacy or online | Private prescriber consultation |
| Licensed for hair loss in the UK? | Yes | Yes | No — licensed only for hypertension |
Evidence and side effects: an honest comparison
Both have real evidence behind them, and both have real, sometimes serious, side effects that shouldn’t be glossed over.
Finasteride’s current UK Propecia product information classifies decreased libido, erectile dysfunction and ejaculation disorder as uncommon. In the main 12-month trials, decreased libido was reported in 1.8% of men taking Propecia versus 1.3% taking placebo, and erectile dysfunction in 1.3% versus 0.7%. Some sexual effects have also been reported after treatment stopped, but their frequency cannot be estimated from spontaneous reports. In May 2026, the MHRA strengthened warnings about psychiatric effects, suicidal thoughts and sexual dysfunction, and advises prescribers to review relevant history and monitor patients. A patient alert card is supplied with finasteride packs.
Minoxidil’s side-effect profile differs depending on how it is taken. Topically, systemic absorption is low and the main reported problems are local, including scalp irritation and unwanted hair growth on nearby skin. Oral minoxidil for hair loss is off-label. The BNF adverse-effect frequencies relate to licensed hypertension treatment and should not be transferred directly to low-dose hair-loss use. In a retrospective study of 1,404 low-dose users, reported systemic effects included lightheadedness (1.7%), fluid retention (1.3%) and a fast heart rate (0.9%), while rare serious events have also been reported.
Using them together
Because finasteride and minoxidil work through different mechanisms, combining them is common in UK private practice. The evidence for added benefit is genuinely time-dependent: shorter trials (around 12 weeks) often show little extra benefit from combining over using minoxidil alone, while longer trials (24 weeks or more) tend to show a bigger combined effect. See our full guide to combining finasteride and minoxidil for the detail, including a UK-specific dataset and its limitations.
Which one is right for you
This isn’t a decision this page can make for you, and any online clinic worth using should say the same. A prescriber will only prescribe finasteride, or off-label oral minoxidil, if it’s suitable for you, based on your health history. Topical minoxidil can reasonably be tried without a prescription, but is still worth discussing with a pharmacist, particularly around realistic timelines and expected results.
See our comparison of UK hair loss clinics for consultation fees and how each service works, or our minoxidil price comparison if you’re only looking at the non-prescription option.