Male-pattern hair loss is extremely common, and two medicines sit at the centre of how it is treated in the UK: finasteride and minoxidil. They work in completely different ways, they suit different people, and neither is a quick fix. This article explains what each one does, what a realistic response looks like, and the side effects and cautions your clinician will talk through before prescribing.
What androgenetic alopecia is
Male-pattern hair loss, known medically as androgenetic alopecia, is driven by a combination of genetics and hormones. In genetically susceptible men, hair follicles at the temples and crown are sensitive to a hormone called dihydrotestosterone (DHT), a more potent derivative of testosterone. Over repeated hair cycles, DHT gradually shrinks these follicles — a process called miniaturisation — so each new hair grows finer, shorter and lighter until the follicle eventually stops producing visible hair. This is why the pattern is so predictable: typically a receding hairline and thinning crown, while the sides and back are usually spared.
Understanding this mechanism explains why the two main treatments target different points in the process: finasteride reduces the hormonal driver, while minoxidil acts on the hair cycle itself.
Ruling out other causes first
Before assuming hair loss is androgenetic, it is worth being sure that is what it is. Sudden, diffuse shedding across the whole scalp — rather than the typical hairline-and-crown pattern — can point to telogen effluvium, a temporary shedding triggered by illness, stress, surgery, rapid weight loss or a new medication. Thyroid problems, low iron and other nutritional deficiencies can also cause or worsen thinning, and these respond to treating the underlying issue rather than to finasteride or minoxidil.
This matters because the treatments are not interchangeable: a medicine aimed at DHT will not help hair loss caused by low iron. A clinician may ask about your history and, where appropriate, arrange blood tests before recommending treatment, so that the plan matches the actual cause rather than the assumed one.
How finasteride works on DHT
Finasteride is an oral tablet that inhibits the enzyme 5-alpha reductase, which converts testosterone into DHT. By blocking this enzyme, finasteride substantially lowers the level of DHT in the scalp and bloodstream. With less DHT reaching the follicles, the miniaturisation process slows and, in many men, partially reverses — allowing thinning hair to thicken again and slowing further loss.
It is taken once daily at the standard 1 mg dose licensed for hair loss. A related, more potent medicine, dutasteride, blocks the enzyme more completely and is sometimes used, though it is not licensed for hair loss in the UK and would be prescribed at a clinician's discretion. Our comparison of finasteride, minoxidil and dutasteride explains where each fits.
Dose matters. The 1 mg tablet is the strength studied and licensed for hair loss; a 5 mg version of finasteride exists but is used for an enlarged prostate, and taking more than the recommended hair-loss dose does not improve results while it can increase the chance of side effects. A topical form of finasteride, applied to the scalp, is also emerging as an option that may reduce how much reaches the rest of the body, though its availability and evidence base are still developing and a clinician can advise whether it is appropriate for you.
How minoxidil works
Minoxidil takes a completely different approach. Most familiar as a topical solution or foam applied directly to the scalp, it does not touch DHT at all. Instead it is thought to prolong the anagen (active growth) phase of the hair cycle and improve blood flow to the follicles, encouraging existing hairs to grow for longer and helping miniaturised follicles produce thicker hair. A low-dose oral form is also used off-label under clinical supervision.
Because finasteride and minoxidil work through separate mechanisms — one hormonal, one on the growth cycle — they are often used together, and many men get a stronger combined response than with either alone. Whether that combination is appropriate for you is a clinical decision.
Realistic expectations and timelines
Patience is essential with both treatments. Hair grows slowly, so neither medicine shows its effect quickly. It usually takes at least three to six months of consistent daily use before any change is visible, and closer to a year to judge the full response. A common early surprise is a temporary increase in shedding when starting minoxidil, as follicles synchronise into a new growth phase; this settles and is not a sign of failure.
It is also important to be clear about what "response" means. For most men the realistic goal is to halt or slow the loss and regain some density — not to restore a full adolescent head of hair. Benefits also depend on continued use: if either medicine is stopped, the DHT-driven process resumes and gains are usually lost within several months. These are ongoing medical treatments, not a cosmetic promise. Our guide on how long finasteride takes to work goes into the timeline in more detail.
It helps to understand the hair cycle behind these timelines. At any moment each follicle is either growing, resting or shedding, and treatment works by nudging more follicles into — and keeping them in — the growing phase. Because that shift plays out over whole cycles rather than days, the early months can feel as though nothing is happening even while the groundwork is being laid, which is exactly why persistence through the first six months matters so much.
Getting the most from treatment
Consistency is the single biggest factor in how well these medicines work. Because hair cycles are slow, missing doses or stopping and starting undermines the response, so it helps to attach the daily routine to an existing habit — brushing your teeth, for instance. Taking dated photographs every few months under similar lighting is a practical way to track change objectively, since day-to-day mirror-watching rarely reveals the gradual difference.
It is reasonable to review progress with a clinician at around six months and again at a year. If there has been no response by then despite consistent use, it is worth revisiting the diagnosis, checking how regularly the treatment has been used, and discussing whether adding the second medicine or adjusting the plan makes sense. Setting expectations at the outset makes this review far less disheartening.
Side effects, monitoring and who should not take these
Finasteride is generally well tolerated, but it carries recognised side-effect considerations that every patient should discuss with a clinician before starting. A small proportion of men report sexual side effects such as reduced libido or erectile difficulties; for most these resolve on stopping, though there has been discussion about rarely persistent symptoms, and mood changes have also been reported. Finasteride must not be taken or handled by women who are or may become pregnant, because lowering DHT can affect the development of a male foetus. It can also lower PSA blood-test readings, which is relevant if you are ever assessed for prostate concerns — so your clinician needs to know you take it.
Topical minoxidil most commonly causes scalp irritation, dryness or itching, and occasionally unwanted facial hair growth if it spreads beyond the scalp. Oral minoxidil, being systemic, needs closer monitoring for effects such as fluid retention or a faster heartbeat, which is why it is used only under supervision. For both medicines, suitability is decided clinically — based on your health, other medicines and expectations — rather than being something to start unsupervised. You can read more across the Farmeci Men's Health and Skin & Hair libraries.