How hair loss treatments work
Plain-English explainers for the two medications behind every modern hair loss plan, and why combining them is usually better than either alone.
The basic problem we're fixing
In male and female pattern hair loss (androgenetic alopecia), the issue isn't that hair stops growing. The issue is that follicles in genetically susceptible scalp areas shrink: each growth cycle produces a slightly finer, slightly shorter hair, until eventually the follicle stops producing visible hair at all.
The hormone driving that shrinkage is dihydrotestosterone (DHT), a downstream product of testosterone. Modern hair loss treatment attacks the problem from two angles: lowering DHT to stop the damage, and pushing the surviving follicles to grow harder.
Those two angles are what finasteride and minoxidil do, respectively.
Finasteride
Stop DHT being made in the first place
Finasteride is a once-daily oral tablet that blocks the enzyme 5-alpha reductase. That enzyme is what converts testosterone into DHT. Block the enzyme, you get less DHT, and the follicle shrinkage that DHT causes slows down or reverses.
Around 80% of patients on finasteride stabilise their hair loss within twelve months, and a meaningful proportion (approximately 48% at 12 months and 66% at 24 months in the Kaufman 1998 trial) see visible regrowth. The effect builds slowly: most people see stabilisation by month three and visible improvement by month six.
Side effects require honest discussion at clinical review. Sexual side effects (reduced libido, erectile dysfunction, ejaculation disorders) and mood changes (low mood, anxiety, depression and rarely suicidal thoughts) have been reported. The MHRA Drug Safety Updates on finasteride (29 April 2024 and 11 May 2026) introduced patient alert cards into finasteride packs and recognise that sexual dysfunction may persist after discontinuation in a small number of cases. The 2026 update extended precautionary advice to dutasteride. Your clinician will walk you through the full picture before prescribing, and you should stop and seek advice if any of these effects occur. Finasteride is not licensed for women and must not be handled (as a crushed or broken tablet) by women who are or may become pregnant.
How it works
How it works
Minoxidil
Push the follicle to grow harder, longer
Every hair follicle cycles through three phases: a long growth phase (anagen), a short transition phase (catagen), and a resting phase (telogen) where the hair eventually sheds. In pattern hair loss, the growth phase gets shorter each cycle, so hairs are finer and don't grow as long before they fall.
Minoxidil extends the growth phase and may also improve blood flow to the follicle. The full mechanism is still being studied but the clinical evidence is strong: most patients on combination finasteride + minoxidil see meaningfully better results than either alone.
Available as a topical solution applied to the scalp daily, or as a low-dose oral tablet. The oral form is prescribed off-licence in the UK for hair loss (its licensed use is for high blood pressure) but is supported by a growing evidence base and has improved adherence for many patients who struggle with the topical. Your clinician will explain the options, including off-licence status, and recommend the right form for you.
Why we usually combine them
Finasteride and minoxidil attack the problem from completely different angles. Finasteride stops the damage being done. Minoxidil makes the surviving follicles grow harder. Together they cover both halves of the equation.
Trial data and clinical experience both show that combination therapy produces meaningfully better results than either alone for most patients with androgenetic alopecia. It's the regimen we typically build into the Advanced plan, and the one most patients on the Essentials plan upgrade to after seeing how things respond.
There are situations where we prescribe only one (or neither). A clinical review is the only way to know what's right for your case.
A note on side effects. Both medications have well-documented side-effect profiles. The vast majority of patients tolerate them without issue, but a small minority experience side effects that warrant adjusting or stopping treatment. Your clinician will discuss the full picture honestly at clinical review , informed consent is part of the standard of care.
Who these medications will not help
Most pages about hair loss treatment only describe who they work for. That is the easier page to write and the less useful one to read. These medicines are genuinely effective for the thing they treat, and there are several situations where they will not do what someone is hoping, and one where taking them instead of something else causes permanent harm.
They hold on to hair better than they bring it back
This is the single most common mismatch of expectations. Finasteride and minoxidil are far more reliable at slowing or stopping further loss than at regrowing what has already gone. A good number of men on treatment look broadly the same in two years as they do today, and that is the treatment working, not failing. Where regrowth does happen it is most likely at the crown and mid-scalp, and least likely at a receded frontal hairline.
They cannot replace a follicle that is no longer there
These drugs rescue follicles that are miniaturising: still present, producing finer and shorter hairs each cycle. They cannot create new ones. Where an area has been completely smooth for years, there is usually nothing left to rescue, and no dose or combination changes that. On the Norwood scale, treatment tends to have most to work with in the earlier stages, and progressively less as loss becomes advanced and long-established. If the goal is coverage of an area that is already bare, that is a surgical question rather than a medical one.
They do not treat scarring alopecias, and using them alone can cost you hair
Conditions such as frontal fibrosing alopecia, lichen planopilaris and central centrifugal cicatricial alopecia destroy the follicle through inflammation and replace it with scar tissue. That damage is permanent. Finasteride and minoxidil do nothing about the inflammation driving it, so taking them alone can mean months pass while follicles are still being lost. Signs worth taking seriously are a hairline moving back in a band with loss of the eyebrows, redness or scaling around the follicles, itching or burning, or smooth shiny patches with no visible pores. If any of that fits, the priority is assessment, sometimes with a biopsy, not a prescription.
They are the wrong answer for sudden diffuse shedding
Hair coming out all over the scalp over a few weeks, rather than thinning in a pattern, is more often telogen effluvium: a reaction to illness, surgery, childbirth, rapid weight loss, low iron or a thyroid problem. It usually recovers once the cause is dealt with, and treating it with finasteride addresses nothing. Bloodwork is the useful first step here.
They do not treat alopecia areata
Well-defined round or oval bald patches appearing quickly are usually alopecia areata, an autoimmune condition with an entirely separate treatment pathway. It is not androgenetic hair loss and does not respond to DHT blockade.
Two other things worth knowing before starting. Judge it at twelve months, not three. Shedding in the first two months is common and is not the treatment failing. And the effect depends on continuing. Stop, and hair held on to by treatment is generally lost over the following six to twelve months, arriving at roughly where you would have been without it. That is worth deciding on deliberately at the start rather than discovering later.
If any of the above sounds like your situation, our prescriber will say so rather than issue a prescription that will not help. Depending on what is going on that may mean bloodwork to find a treatable cause, a scarring alopecia workup, or a surgical opinion. Being told a medication is not right for you is a better outcome than a year spent finding out.