DHT and Hair Loss: The Actual Science, Explained Simply
DHT is the main driver of male pattern baldness. Here's what it is, how it shrinks your hair follicles, and what you can do about it.
If you’ve read anything about hair loss, you’ve encountered DHT. It gets blamed for everything. But what is it, how does it actually cause hair loss, and — more usefully — what can you do about it?
What Is DHT?
DHT stands for dihydrotestosterone. It’s an androgen — a hormone in the same family as testosterone.
Your body produces DHT from testosterone through an enzyme called 5-alpha reductase. About 10% of your testosterone gets converted to DHT. DHT is more potent than testosterone — it binds to androgen receptors more strongly and for longer.
DHT plays important roles in your body: it’s involved in prostate development, body hair growth, and sexual maturation during puberty. The problem is that hair follicles on your scalp, if genetically susceptible, respond to DHT very badly.
How DHT Causes Hair Loss
Hair follicles on the scalp have androgen receptors. In men with androgenic alopecia (male pattern baldness), these receptors are genetically sensitive to DHT.
When DHT binds to the receptors in susceptible follicles, it triggers a process called follicular miniaturisation. Here’s what happens:
- DHT binding causes changes in the follicle’s behaviour
- Each hair growth cycle, the follicle produces a slightly thinner, shorter hair
- Over years and decades, follicles miniaturise until they produce only fine vellus hairs (“peach fuzz”)
- Eventually, the follicle can stop producing hair entirely
This is why hair loss happens gradually — it’s the accumulated effect of repeated DHT-follicle interactions over many hair growth cycles.
Why Only Some Follicles Are Affected
Notice that men with androgenic alopecia lose hair in characteristic patterns — the temples, crown, and top of the scalp — while follicles on the sides and back of the head remain unaffected.
This is because follicles in different areas of the scalp have different genetic programming. The follicles on the sides and back are simply not sensitive to DHT, regardless of how much of it is circulating in your blood.
This is why hair transplants work: surgeons take DHT-resistant follicles from the back and sides and transplant them to thinning areas. Because the follicles themselves are resistant, they continue growing in their new location.
Is It About Testosterone or DHT?
Common misconception: bald men have more testosterone. Generally not true.
What matters isn’t how much DHT you have — it’s how sensitive your scalp follicles are to DHT. Some men with relatively low DHT levels go bald; some with high DHT keep full heads of hair. The genetics of follicle sensitivity is the key variable, not the absolute amount of DHT.
The Genetics of Susceptibility
Androgenic alopecia is highly heritable. The old “look at your mother’s father” rule has some basis but is an oversimplification — relevant genes come from both parents.
If the men in your family — father, uncles, grandfathers on both sides — go bald, your risk is elevated. The earlier it starts in your family, the earlier and more dramatically it tends to manifest in you.
What Can You Do About DHT?
If DHT is the problem, blocking DHT is an obvious solution.
Finasteride (Propecia) works by inhibiting 5-alpha reductase — the enzyme that converts testosterone to DHT. It reduces DHT levels in the scalp by around 60-70%. Clinical evidence shows it stops hair loss in the majority of men and produces regrowth in many.
Dutasteride is a more aggressive 5-alpha reductase inhibitor that reduces DHT by around 90%. More effective than finasteride in studies, but with a higher side effect profile. Prescribed off-label for hair loss.
Topical finasteride delivers the drug directly to the scalp, reducing systemic exposure and therefore reducing the risk of systemic side effects. Increasingly popular.
Ketoconazole shampoo has some evidence of mild anti-androgenic effects on the scalp. Not a replacement for finasteride but can be used as an adjunct.
The Bottom Line
DHT miniaturises hair follicles in genetically susceptible men. The susceptibility is determined by your genetics, not how much DHT you have. The most effective treatments — finasteride, dutasteride — work by reducing DHT. Minoxidil works differently and doesn’t block DHT, which is why it’s often used in combination with DHT blockers.
Understanding this mechanism helps you understand why there’s no “natural” quick fix for male pattern baldness — you’re working against a genetic process driven by a normal hormone. The options are legitimate treatments, lifestyle optimisation around those treatments, or acceptance.
