Androgen receptor expression describes how many androgen receptors a cell makes and how sensitive it therefore is to hormones such as testosterone and dihydrotestosterone. In hair, this is the single best explanation for why some people thin at the temples and crown while others keep a full head into old age. It is not about how much hormone you have. It is about how strongly particular follicles are wired to respond to it.

What is androgen receptor expression in plain English?

An androgen receptor is a protein inside a cell that binds male hormones. Once bound, the receptor moves into the cell nucleus and changes which genes that cell switches on. Expression simply means how much of that receptor the cell produces. High expression means a loud response to a given amount of hormone; low expression means a quiet one.

The practical consequence is that two people with identical hormone levels can have completely different hair. One has follicles that barely register the signal, the other has follicles that respond strongly. This is why the old belief that balding indicates high testosterone does not hold up.

The hormone that matters most here is dihydrotestosterone, usually shortened to DHT, which is converted from testosterone by an enzyme called 5-alpha reductase. DHT binds the androgen receptor considerably more tightly than testosterone does, so in follicles with high receptor density its effect is amplified.

Why does androgen receptor expression matter for hair?

Because of what the receptor signal does to the hair cycle. Every follicle runs through a growth phase lasting years, a brief transition, and a resting phase before the hair releases and the cycle restarts. In a susceptible follicle, repeated androgen signalling progressively shortens the growth phase.

Shorter growth phase means the hair has less time to grow before it is shed, so it comes out shorter. Alongside this the follicle itself gradually shrinks, a process called miniaturisation, so each successive hair is finer and less pigmented than the one before. Run that over many cycles and a thick terminal hair becomes a short, wispy, barely visible one. The follicle is still there for a long time before it finally stops, which is why density loss is gradual rather than sudden.

Research published in the International Journal of Biological Sciences in 2023 described one signalling route involved, in which androgen receptor activity in the dermal papilla cells at the base of the follicle influences a microRNA called miR-221 and the growth factor IGF-1. The detail matters less than the direction: the receptor is not just present, it actively changes the instructions the follicle receives.

Why does hair thin in a pattern rather than all over?

This is the part that puzzles most people, and androgen receptor sensitivity is the answer. Follicles are not uniform. Those on the frontal hairline, temples and vertex carry noticeably higher receptor density than those on the occipital scalp at the back and sides. The follicles at the back are comparatively indifferent to androgens.

That regional difference is why the pattern is so recognisable, why it is consistent across families, and why hair transplants work at all: hair moved from the back to the front tends to keep the low sensitivity it was born with rather than adopting the behaviour of its new neighbourhood.

In men the pattern typically starts at the temples and crown. In women it more often shows as diffuse widening of the central parting with the frontal hairline preserved, a distinction covered in the clinical literature on female pattern hair loss. Our guides on crown thinning and protecting your hairline go into what each looks like early on.

Is androgen receptor expression inherited?

Largely, yes. The androgen receptor gene sits on the X chromosome, which men inherit from their mother, and variation in and around that gene is one of the strongest known genetic associations with pattern hair loss. That is where the folk wisdom about looking at your maternal grandfather comes from.

But the folk wisdom is only half right, and worth correcting. Pattern hair loss is polygenic: many genes contribute, and a good number sit on other chromosomes inherited from either parent. A man whose father lost his hair early is at raised risk regardless of what his mother's family looked like. Looking at one relative and drawing a conclusion is not reliable.

Does high testosterone mean more hair loss?

No, and this misunderstanding causes a lot of unnecessary worry. Men with pattern hair loss usually have entirely normal circulating testosterone. What differs is local conversion to DHT within the scalp and, above all, how many receptors those follicles express.

The corollary is important: a normal testosterone result does not mean your hair loss is not androgen driven, and asking for a testosterone test to explain thinning hair is usually the wrong question. In women the hormonal picture is more layered, since oestrogen and progesterone changes around pregnancy and the menopause interact with androgen sensitivity, which is one reason a 2024 review in Biomedicines frames non-scarring hair loss as a hormonal system rather than a single hormone.

If your hair is changing and you want something genuinely useful measured, ferritin, full blood count and thyroid function are far more informative for most people, and your GP can arrange them.

Hair loss, hair shedding and hair breakage are three different things

Androgen receptor sensitivity is relevant to exactly one of these, so establishing which you have comes first.

• Hair loss is follicular miniaturisation. Hairs get progressively finer and shorter over months and years, the parting widens, the ponytail thins. This is the one androgens drive, and it is gradual.
• Hair shedding is cyclical release. A large number of follicles enter the resting phase together after illness, childbirth, a crash diet or a stressful period, then release two to three months later. Hairs come out full thickness with a pale bulb at the root, and it usually recovers on its own. See our guide to telogen effluvium.
• Hair breakage is fibre failure. The hair snaps along its length, leaving short pieces with no bulb, plus frizz and split ends. Heat, bleach, tight styling and rough handling cause it. Hormones have nothing to do with it.

The quickest check is the root end of a fallen hair. A small pale bulb means it was shed whole. A blunt or frayed end with no bulb means it broke. Fine, short, wispy hairs where thick ones used to be point to miniaturisation. If it is the third, our guide to what triggers androgenic alopecia covers what tends to accelerate it.

What can you actually do about androgen receptor expression?

Honestly, you cannot change it. Receptor sensitivity is set by your genes and no product alters it. What follows from that is a short, clear set of realistic options.

Licensed medical options exist and are not our department. There are regulated medicines that act on this pathway. We do not sell them, we are not qualified to advise on them, and we are not going to discuss them on a shampoo company's website. If you want to explore that route, speak to your GP or a pharmacist, who can talk you through what is suitable and what the trade offs are.

Get the timing right. Miniaturisation is gradual and easier to slow early than to address late. If you have noticed a change, looking into it sooner is better than waiting to see.

Protect what you have. This is where cosmetic care genuinely earns its place. Hair that is already fine because of miniaturisation is more vulnerable to breakage, so every hair lost to snapping makes thinning look worse than it is. Reducing breakage does not change follicle biology, but it does mean you keep more of the hair you are still growing.

Look after the scalp. Work in the International Journal of Trichology has argued that the scalp is the environment in which the fibre forms before it emerges, and that oxidative stress there is worth taking seriously. A comfortable, clean, well cared for scalp is not a fix for androgen sensitivity, but neglecting it helps nobody.

Watermans products are 100% cosmetic and do not treat medical hair loss. Individual results may vary.

How do the different explanations of thinning compare?

Which Watermans products fit here, and what they cannot do?

Let us be direct, because this topic attracts a lot of nonsense. Nothing we make changes androgen receptor sensitivity, alters 5-alpha reductase, or affects the hormonal signalling described on this page. Any brand telling you a shampoo does that is overstating it. What our products do is cosmetic: they clean the scalp, condition the fibre and reduce breakage, so hair looks fuller and you keep more of the length you grow.

Grow Me® Shampoo, £14.95

Sulfate free daily shampoo with biotin, caffeine, rosemary and niacinamide. It reduces breakage so finer hair holds its length and looks fuller. Made in the UK, vegan, and over 5 million bottles sold since 2012.

Grow More® Elixir, Overnight Scalp Serum, £25.50

A leave-on serum for the parting and crown where density has dropped, applied with a minute of scalp massage. Cosmetic support for the scalp and fibre, not a medicine, and not something that acts on the hormonal pathway above.

Frequently Asked Questions About Androgen Receptor Expression

Can you test your androgen receptor expression?

Not usefully as a consumer. Measuring receptor density in scalp follicles is a laboratory research technique, not a service you can buy meaningfully on the high street. Commercial genetic hair tests report risk associations rather than your actual scalp biology, and family history plus a mirror tells you much the same thing for nothing.

Does high testosterone cause baldness?

No. Most men with pattern hair loss have normal testosterone. The difference lies in local conversion to DHT in the scalp and in how many androgen receptors those particular follicles express, which is inherited.

Do women have androgen receptors in their hair follicles?

Yes, and androgen sensitivity contributes to female pattern hair loss too. The presentation differs, typically as diffuse widening of the central parting with the frontal hairline preserved, and the hormonal picture is more complex because oestrogen and progesterone also shift across life.

Can you lower androgen receptor sensitivity naturally?

There is no good evidence that any diet, supplement or topical ingredient meaningfully changes receptor expression in scalp follicles. Claims of that kind are common online and are not supported. Be sceptical of anything promising it.

Why does hair at the back of the head never thin?

Occipital follicles express far fewer androgen receptors than those on the temples and crown, so they barely respond to the same hormonal signal. That regional difference is also why transplanted hair from the back tends to persist in its new position.

Is pattern hair loss inherited only from your mother's side?

No. The androgen receptor gene is on the X chromosome, which is why the maternal line matters, but pattern hair loss is polygenic and genes from your father contribute too. Judging your risk from a single relative is unreliable.

How fast does miniaturisation happen?

Slowly, over years rather than months. Each cycle produces a slightly finer, shorter hair, so change is easy to miss day to day and obvious in photographs a year apart. That is exactly why tracking with consistent photos is more useful than staring in the mirror.

Does wearing a hat or washing daily make it worse?

Neither. Hats do not cause pattern hair loss, and daily washing does not either. Washing simply gathers the hairs you were going to shed anyway, which is why people who wash less often see more hair at once and blame the shampoo.

Conclusion: The Short Version on Androgen Receptor Expression

Androgen receptor expression is how strongly a follicle is wired to respond to androgens, and it is the reason pattern hair loss follows a pattern at all. Follicles at the temples and crown carry more receptors than those at the back, so the same hormone level produces thinning in one region and nothing in another. The sensitivity is inherited, it is not caused by high testosterone, and no product on the market changes it.

What is worth doing is practical. Work out whether you are seeing miniaturisation, shedding or breakage, because they are not the same problem. Ask your GP about ferritin and thyroid function if anything changed quickly. Take consistent photographs so you can judge real change. And handle the hair you do have gently, because breakage is the one part of this you fully control.

Sources & References

• The AR/miR-221/IGF-1 pathway mediates the pathogenesis of androgenetic alopecia. International Journal of Biological Sciences, 2023.
• Male androgenetic alopecia. Anais Brasileiros de Dermatologia, 2025.
• Ramos PM, Miot HA. Female Pattern Hair Loss: a clinical and pathophysiological review. Anais Brasileiros de Dermatologia, 2015.
• The Hormonal Background of Hair Loss in Non-Scarring Alopecias. Biomedicines, 2024.
• NHS. Hair loss, for when to speak to your GP.