Written by Jeremy Isherwood, trichologist. Medically reviewed by Miss Anne Kremer.

Quick answer

DHT (dihydrotestosterone) is a hormone the body makes from testosterone, using an enzyme called 5-alpha reductase. In people who are genetically sensitive to it, DHT acts on hair follicles on the top and front of the scalp and makes them gradually shrink, so each new hair grows back thinner, shorter and lighter. This is the process behind male and female pattern hair loss (androgenetic alopecia). Having DHT is normal; it is the inherited sensitivity of the follicles that decides whether it causes hair loss.

What is DHT?

DHT is an androgen, one of the group of hormones often called "male" hormones, although everyone has them. It is made when the enzyme 5-alpha reductase converts testosterone into DHT. There are two main types of this enzyme, known as type 1 and type 2.

DHT has a stronger effect on the body's androgen receptors than testosterone itself. Before birth it is essential for the normal development of male sex characteristics, and it plays a part in the changes of puberty, such as facial and body hair.

In adult life, DHT keeps acting on tissues that respond to androgens, including the prostate and the hair follicles on the scalp. That is why it matters so much for hair.

How does DHT cause hair loss?

Each hair follicle goes through a repeating cycle: a long growing phase (anagen), a short transition phase, and a resting phase before the hair sheds and a new one starts. You can read more in our guide to the hair growth cycle.

In people with a genetic tendency to pattern hair loss, DHT binds to androgen receptors in follicles on the top and front of the scalp. Over time this does two things:

• It shortens the growing phase. DermNet, the New Zealand dermatology resource, describes DHT shortening anagen from a usual three to six years to just weeks or months.
• It shrinks the follicle. This is called miniaturisation. Each new hair is thinner, shorter and lighter than the one before, until some follicles produce only fine, barely visible hairs.

The result is not usually sudden. The British Association of Dermatologists (BAD) says male pattern hair loss tends to progress very slowly, over several years to decades.

If everyone has DHT, why doesn't everyone go bald?

Because the key factor is how sensitive your follicles are, and that is largely inherited. The BAD says the tendency can come from either or both parents, and more than 190 genes have been identified as contributing. A 2023 genetics review found that twin studies put the heritability of early-onset male pattern hair loss at about 0.8, meaning genes explain most of the variation between people.

This is also why the hair at the sides and back of the head usually survives. Those follicles are typically more resistant to DHT, which is the principle a hair transplant relies on (more on that below).

It also means a blood test showing "normal" or "high" DHT does not, on its own, tell you whether you will lose your hair.

What are the signs of DHT-related hair loss in men?

The BAD describes the usual pattern in men as a receding frontal hairline and loss of hair from the top of the head, with the hair at the sides and back spared. Common signs include:

• Recession at the temples. Male pattern hair loss typically begins with recession at both temples, often forming an "M" shape. Some temple recession is normal as the hairline matures, so see our guide on mature vs receding hairlines.
• Thinning at the crown. The top back of the head thins and a bald spot may appear.
• Finer, shorter hairs. Hairs in the affected areas become thinner and lighter as follicles miniaturise.
• More scalp showing under bright light or when hair is wet.

Doctors often grade male pattern hair loss using the Norwood scale. Our guide to the Norwood scale explains each stage.

How common is it? DermNet reports that up to half of white men have some degree of hair loss by age 50, and possibly as many as 80% by age 70.

Can DHT cause hair loss in women?

Female pattern hair loss is also known as androgenetic alopecia and is the most common type of hair loss in women, but hormones work differently here. The BAD says it is caused by a combination of genetic and hormonal factors, and DermNet notes that the role of androgens is less clear than in men: most women with female pattern hair loss have normal androgen levels in their blood.

The pattern is also different. Women usually get diffuse thinning over the top of the scalp, with a widening parting, while the hairline at the front often stays normal. Many women first notice a thinner ponytail or more scalp showing along the parting.

DermNet reports that around 40% of women show signs of hair loss by age 50, and it becomes more common after the menopause. You can read more in our article on menopausal hair loss.

Some conditions raise androgen levels. Polycystic ovary syndrome (PCOS) is one: the NHS lists hair loss, as well as excess hair growth, among its symptoms. If thinning comes with irregular periods, acne or excess facial or body hair, see your GP.

Can you lower DHT or block its effects?

Some treatments act on DHT and some work in other ways. None is a cure: the BAD says there is no cure for androgenetic alopecia, and the NHS says treatments do not work for everyone and only work for as long as they are used. The NHS also says that most hair loss treatments are not available on the NHS, and it recommends seeing a GP to understand the cause of your hair loss before going to a commercial clinic.

The following is general information, not a recommendation. Any prescription medicine needs a doctor's assessment first.

Finasteride (prescription only)

Finasteride is a prescription-only medicine. It blocks the type 2 form of 5-alpha reductase and reduces DHT levels; one review reports a fall in blood DHT of about 70%. The NHS names it as one of the main treatments for male pattern baldness. The BAD says it may need to be taken continuously for up to 14 months before any benefit is seen, and any benefit is lost when treatment stops.

Side effects. The BAD reports reduced sex drive and erection problems in about 2% of men. In April 2024 the UK medicines regulator, the MHRA, reminded doctors that finasteride has been associated with depression, suicidal thoughts and sexual dysfunction, and that some men have reported sexual side effects that continued after they stopped taking it. A patient alert card was introduced in packs. In May 2026 the MHRA strengthened the product information again. Its advice is that anyone taking finasteride who experiences depression or suicidal thoughts should stop treatment and seek medical advice.

Women. The NHS states that women should not use finasteride. It carries a risk to a male baby's development in pregnancy.

Dutasteride (prescription only, not licensed for hair loss in the UK)

Dutasteride is a prescription-only medicine in the same class as finasteride. It blocks both type 1 and type 2 5-alpha reductase. In the UK it is licensed to treat an enlarged prostate (benign prostatic hyperplasia), not hair loss, so any use for hair loss is "off-label" and a decision for a doctor. The BAD says the extent of any improvement is unclear and side effects may be more frequent than with finasteride. In 2026 the MHRA added a precautionary warning about mood changes to its product information.

Minoxidil

Minoxidil does not act on DHT. It is thought to work by increasing blood flow to the hair follicles, which lets hairs grow for longer.

• Topical minoxidil (a liquid or foam applied to the scalp) can be bought over the counter and can be used by men and women. The BAD says it may help to slow down the progression of hair loss, takes at least 6 and possibly up to 12 months to show a benefit, and the benefit stops if you stop using it. When you start, some people notice a temporary increase in shedding, which NHS hospital leaflets say usually settles within the first six weeks. There is no evidence it is safe when trying to conceive, pregnant or breastfeeding.
• Oral minoxidil (low-dose tablets) is prescription-only and is used for hair loss outside its original licence, so it needs a doctor's assessment first. Side effects, which are dose-related, can include fluid retention, a faster heart rate, dizziness and unwanted hair growth on the face and body.

Other treatments for women

For female pattern hair loss, the BAD also lists anti-androgen medicines such as spironolactone and cyproterone acetate. These are prescription medicines that need a specialist's assessment.

What other things cause hair loss?

Not all thinning is DHT-related, and getting the cause right matters because the treatment is different. The NHS says losing 50 to 100 hairs a day is normal. It lists temporary hair loss caused by illness, stress, cancer treatment, weight loss and iron deficiency. Other causes include:

• Thyroid problems. The NHS lists hair loss among the common symptoms of an underactive thyroid.
• Alopecia areata. The BAD explains that here the immune system mistakenly attacks the hair follicle, typically causing patches of hair loss.
• Stress. Significant stress can trigger a period of increased shedding. See our guide on how to stop hair loss from stress.
• Medicines. Some medicines list hair loss as a side effect. See medications that may cause hair loss.
• Styling and tension. Tight hairstyles and heat damage can cause breakage and a type of hair loss called traction alopecia. See 8 ways you're damaging your hair.

If your hair loss is sudden, patchy, or comes with other symptoms such as tiredness, weight change or an itchy, sore scalp, see your GP.

Can a hair transplant help with DHT hair loss?

A hair transplant does not change your DHT levels. What it does is move follicles from the back and sides of the scalp, where, as the BAD puts it, hair is typically more resistant to miniaturisation by DHT, into thinning areas. Those transplanted follicles tend to keep that resistance in their new position.

It is important to know what a transplant cannot do. Your own (non-transplanted) hair on the top of the head can keep thinning over time, which is why a surgeon will look at your age, family history, how fast your hair loss is moving and how much donor hair you have before recommending surgery.

Every surgery carries risks, and results vary from person to person. FUE leaves small dot scars in the donor area, and FUT (follicular unit transplantation) leaves a fine linear scar.

How FUE Clinics can help

FUE Clinics is a CQC-registered UK hair transplant clinic, and all surgery is carried out in the UK. If you are not sure whether your hair loss is DHT-related, a trichologist consultation can help identify the likely cause.

If a transplant may be suitable, we offer FUE and FUT hair transplants, including hairline and crown work, and hair transplants for women. Hair transplants cost from £1,500 to £6,750 depending on the number of grafts, with 12 months 0% finance available. See our hair transplant cost page for details.

Consultations are free, in person or by video. Call 0330 363 0001 or contact us.

Frequently asked questions

Does high DHT mean I will go bald? Not necessarily. Pattern hair loss depends mainly on how sensitive your hair follicles are to DHT, which is largely inherited, rather than on the amount of DHT alone.

Is DHT hair loss reversible? Follicles that have miniaturised can sometimes produce thicker hair again with treatment, but there is no cure and any benefit from medicines is lost when they are stopped. Results vary, and a doctor can advise on what is realistic for you.

Can women take finasteride? The NHS states that women should not use finasteride. Women with female pattern hair loss should speak to a GP or dermatologist about the options suitable for them.

Does stress raise DHT? There is no good evidence we could find that stress causes pattern hair loss through DHT. Stress can, however, trigger a separate type of temporary shedding.

Why are transplanted hairs less affected by DHT? Hair is usually taken from the back and sides of the scalp, where follicles are typically more resistant to DHT, and they tend to keep that resistance after being moved.

Should I see a GP first? Yes, if you are worried. The NHS recommends seeing a GP to understand what is causing your hair loss before going to a commercial hair clinic.

Sources

• NHS, Hair loss: https://www.nhs.uk/symptoms/hair-loss/
• NHS, Polycystic ovary syndrome, symptoms: https://www.nhs.uk/conditions/polycystic-ovary-syndrome-pcos/symptoms/
• NHS, Underactive thyroid, symptoms: https://www.nhs.uk/conditions/underactive-thyroid-hypothyroidism/symptoms/
• British Association of Dermatologists, Hair loss male pattern (androgenetic alopecia): https://www.bad.org.uk/pils/hair-loss-male-pattern-androgenetic-alopecia
• British Association of Dermatologists, Hair loss female pattern (androgenetic alopecia): https://www.bad.org.uk/pils/hair-loss-female-pattern-androgenetic-alopecia
• British Association of Dermatologists, Alopecia areata: https://www.bad.org.uk/pils/alopecia-areata/
• MHRA, Finasteride: reminder of the risk of psychiatric side effects and of sexual side effects (29 April 2024): https://www.gov.uk/drug-safety-update/finasteride-reminder-of-the-risk-psychiatric-side-effects-and-of-sexual-side-effects-which-may-persist-after-discontinuation-of-treatment
• MHRA, MHRA strengthens safety warnings for finasteride and dutasteride (11 May 2026): https://www.gov.uk/government/news/mhra-strengthens-safety-warnings-for-finasteride-and-dutasteride
• Gloucestershire Hospitals NHS Foundation Trust, Minoxidil for hair loss: https://www.gloshospitals.nhs.uk/your-visit/patient-information-leaflets/minoxidil-for-hair-loss-ghpi1649/
• Royal Berkshire NHS Foundation Trust, Minoxidil for hair loss (October 2025): https://www.royalberkshire.nhs.uk/media/n3onzj1d/minoxidil-for-hair-loss_oct25.pdf
• DermNet, Male pattern hair loss: https://dermnetnz.org/topics/male-pattern-hair-loss
• DermNet, Female pattern hair loss: https://dermnetnz.org/topics/female-pattern-hair-loss
• MedlinePlus Genetics, 5-alpha reductase deficiency: https://medlineplus.gov/genetics/condition/5-alpha-reductase-deficiency/
• Escamilla-Cruz M et al. Use of 5-Alpha Reductase Inhibitors in Dermatology: A Narrative Review. Dermatol Ther, 2023: https://pmc.ncbi.nlm.nih.gov/articles/PMC10366043/
• Henne SK, Nöthen MM, Heilmann-Heimbach S. Male-pattern hair loss: comprehensive identification of the associated genes as a basis for understanding pathophysiology. Med Genet, 2023: https://pmc.ncbi.nlm.nih.gov/articles/PMC10842561/