Hair loss is the grooming subject with the widest gap between what is sold and what is supported. Almost every other topic in this journal involves shades of grey. This one has an unusually clear line running through it, because two treatments have been through large randomised trials and regulatory review, and most of the rest have been through a marketing department.
This article is about male pattern hair loss specifically, which is androgenetic alopecia. It is not about patchy loss, sudden shedding, loss with scaling or scarring, or loss with symptoms elsewhere. Those have different causes and need a GP rather than an article.
What is actually happening to the follicle
Male pattern loss is not follicles dying. It is follicles shrinking, a process called miniaturisation. Each follicle cycles through a growth phase, a transition phase and a resting phase, then sheds and starts again. In androgenetic alopecia, the growth phase gets shorter with every cycle and the follicle produces a progressively finer, shorter, less pigmented hair until it produces something closer to fine vellus down.
The driver is dihydrotestosterone, a more potent androgen converted from testosterone by the enzyme 5-alpha reductase. What is inherited is not high hormone levels but follicle sensitivity, and that sensitivity is regionally distributed across the scalp. This is why the pattern is a pattern, receding at the temples and thinning at the crown while the band around the back and sides persists. Those follicles are simply not sensitive, which is also the entire biological basis of hair transplantation.
The crucial consequence: a miniaturised follicle can be rescued, a dead one cannot. Treatment protects what is left far better than it recovers what is gone.
The two treatments with strong evidence
Topical minoxidil
Minoxidil was developed as an oral antihypertensive and its effect on hair was discovered as a side effect. Applied to the scalp it prolongs the growth phase and increases follicle size, probably through vasodilation and effects on potassium channels in the follicle, though the mechanism is still not fully settled.
Practical points that determine whether it works for a given man:
- It is applied to the scalp, not the hair, twice daily for solutions and foams at the standard strength. Consistency matters more than quantity.
- An increase in shedding in weeks two to eight is expected and is a sign that resting follicles are being pushed into a new growth phase. Most men who stop, stop here.
- Meaningful assessment is at four to six months. Peak effect is around a year.
- It is available over the counter in the UK. Propylene glycol in some solutions is a frequent cause of scalp irritation, and foam formulations generally omit it.
Oral finasteride
Finasteride inhibits type II 5-alpha reductase, reducing conversion of testosterone to dihydrotestosterone and therefore reducing the signal that drives miniaturisation. It is a prescription only medicine in the UK and requires a consultation with a prescriber.
It is the more effective of the two for slowing progression in most men, and the two are often used together because their mechanisms are unrelated. It also carries a side effect profile that must be discussed with a prescriber rather than read about in an article, including sexual side effects reported by a minority of users, and there has been ongoing regulatory attention to psychiatric side effects. The Medicines and Healthcare products Regulatory Agency publishes the current UK safety position, and that, together with a prescriber, is the correct source rather than a forum.
The middle ground, plausible but weaker evidence
| Intervention | Evidence | Realistic expectation |
|---|---|---|
| Topical minoxidil | Strong, multiple randomised trials, licensed | Slows loss, partial regrowth, needs 6 to 12 months |
| Oral finasteride | Strong, multiple randomised trials, prescription | Slows or halts progression in most users |
| Low level laser therapy | Moderate, several small trials, heterogeneous devices | Modest density improvement, high cost, slow |
| Microneedling | Emerging, small trials, mostly as an adjunct | May improve response to topicals, protocols vary widely |
| Ketoconazole shampoo | Limited, small studies, plausible anti-inflammatory route | Scalp health support, not a regrowth treatment |
| Oral supplements | Weak unless a deficiency exists | Corrects deficiency only, no effect on the androgen pathway |
| Caffeine shampoos | Weak, in vitro and short contact time | Not a substitute for a licensed treatment |
| Scalp massage alone | Very weak, tiny uncontrolled studies | Pleasant, not a treatment |
What does not work, and why it still sells
Thickening shampoos work by depositing polymers and by swelling the hair shaft temporarily. The effect is real, immediate and entirely cosmetic. It disappears at the next wash and it does not touch the follicle.
Supplements sold for hair are the largest category by volume and the smallest by evidence. Correcting a genuine deficiency, most commonly iron in men who have a reason to be low, or vitamin D, or protein in someone eating very little of it, can improve hair quality. Taking those same nutrients when your levels are normal does nothing, and some, notably high dose selenium and excess vitamin A, are associated with hair shedding rather than growth. Biotin has almost no evidence base outside genuine biotin deficiency, which is rare, and it can interfere with certain laboratory blood tests.
The reason these sell is timing. Hair loss is gradual and shedding fluctuates with the seasons and with stress, so anything started during a heavy shed will appear to work when the shed reverts to baseline on its own. That is regression to the mean, and it is the engine of the entire category.
Why starting early matters more than anything else
Because treatment protects existing follicles far more reliably than it revives collapsed ones, the same treatment produces very different outcomes depending on when it starts. A man who begins at the first temple recession keeps most of what he has. The same man beginning after a decade of loss keeps a much thinner field. It is the same compounding logic that governs sun protection, set out in what changes in men's skin and when, and it is worth adding that a receding hairline moves previously shaded scalp into direct sunlight, so daily sun protection becomes a scalp question as well as a face one.
This is uncomfortable, because early loss is when denial is easiest. The practical suggestion is photographic. Take a photograph of your hairline and your crown, in the same light, from the same distance, every three months. Human memory is completely unreliable about gradual change, and a photo series is the only way to know whether a treatment is working or whether you are simply having a good hair day.
When it is not male pattern loss
See a GP rather than reaching for a treatment if any of the following apply.
- Loss in discrete round patches rather than a diffuse pattern.
- Sudden heavy shedding across the whole scalp, particularly a few months after illness, surgery, significant weight loss or a major stressor.
- Redness, scaling, pustules, pain or itching in the affected area.
- Areas where the skin looks smooth and shiny with no visible follicle openings, which can indicate scarring alopecia and is time critical.
- Loss of eyebrow, eyelash or body hair alongside scalp loss.
Patient information on the different types of alopecia is published by the British Association of Dermatologists, and the NHS sets out which presentations warrant assessment.
Scalp care while you are treating
A scalp is skin, and inflamed skin is not a good environment for follicles. Flaking and seborrhoeic dermatitis are extremely common alongside pattern loss, and the same antifungal actives discussed in our feature on beard skin apply above the hairline. Keeping the scalp calm will not regrow hair, but persistent inflammation makes topicals harder to tolerate and makes the loss look worse.
Two small mechanical points. Aggressive daily brushing of already fine hair increases breakage, which reads as further loss. And tight, sustained tension from certain styles can cause traction alopecia, which is a separate and preventable process from androgenetic loss.