Antiandrogen Therapy: Uses, Side Effects and Options
Antiandrogen therapy is a group of prescription treatments that either block androgen receptors or reduce how much androgen the body produces. Androgens include testosterone and dihydrotestosterone, usually shortened to DHT. Clinicians use these medicines in prostate cancer, androgenetic alopecia, hirsutism, hormonal acne and feminising gender affirming hormone therapy. Every drug named on this page is prescription only, several are used off label, and all of them require a prescriber, monitoring and a proper conversation about risks.
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This article is general information, not medical advice, and it cannot tell you whether a medicine is right for you. Antiandrogens affect the whole body, not just hair. Do not start, stop or change any prescribed medicine on the strength of an article. Speak to your GP, dermatologist, endocrinologist, oncologist or gender identity service.
Key takeaways
- Antiandrogens work in two main ways: blocking the androgen receptor, or lowering androgen production.
- 5-alpha-reductase inhibitors such as finasteride and dutasteride reduce DHT rather than blocking the receptor, so they are a distinct class.
- In the UK, finasteride 1 mg is licensed for male pattern hair loss in men, is not licensed for women, and must not be handled by anyone who could become pregnant if tablets are crushed or broken.
- Spironolactone is widely used for hirsutism and female pattern hair loss, but in the UK that use is off label.
- Effects on hair take six to twelve months to judge, and they reverse if treatment stops.
- Monitoring is part of the treatment, not an optional extra. Blood tests are routine on several of these drugs.
What is antiandrogen therapy?
Antiandrogen therapy is any treatment that reduces the biological effect of androgens. Androgens are the hormones responsible for typically male characteristics, and everyone produces them, including women, in smaller amounts. Where a condition is androgen driven, lowering that signal can change how the tissue behaves.
Two levers exist. A receptor blocker sits on the androgen receptor so testosterone and DHT cannot activate it. A production reducer lowers the amount of hormone available in the first place, either by blocking an enzyme, suppressing the signal from the brain, or blocking synthesis directly.
How do androgens cause pattern hair loss?
In androgenetic alopecia, the follicle is genetically sensitive to DHT rather than the DHT level being abnormal. Over repeated growth cycles the affected follicles miniaturise, producing progressively finer, shorter, less pigmented hairs until they stop producing a visible hair at all. This is why the condition is gradual, patterned and, in men, follows a predictable frontal and crown distribution.
That mechanism explains both what antiandrogens can do and what they cannot. Reducing DHT can slow miniaturisation and, in some people, partially reverse it while treatment continues. It does not restore follicles that have been dormant for many years, and any benefit fades once the drug is stopped. Our explainer on what triggers androgenic alopecia covers the biology in more depth, and our guide to pattern hair loss in men and women covers the staging.
What are the main classes of antiandrogen medicines?
Four groups cover almost all clinical use. They differ in mechanism, in what they are licensed for, and in how closely they need to be monitored.
| Class | Examples | How it works | Mainly used for |
|---|---|---|---|
| Androgen receptor blockers, steroidal | Spironolactone, cyproterone acetate | Occupy the receptor and, for cyproterone, also lower androgen levels | Hirsutism, hormonal acne, female pattern hair loss, feminising hormone therapy |
| Androgen receptor blockers, non steroidal | Bicalutamide, flutamide, enzalutamide, apalutamide | Bind the receptor without activating it | Prostate cancer, under specialist care |
| 5-alpha-reductase inhibitors | Finasteride, dutasteride | Block conversion of testosterone to DHT, so they lower DHT rather than blocking the receptor | Male pattern hair loss, benign prostatic hyperplasia |
| Androgen suppression | Leuprorelin, goserelin, degarelix, abiraterone | Shut down or block hormone production upstream | Advanced prostate cancer, and some gender affirming protocols |
The third row matters more than people realise. Finasteride and dutasteride are often lumped in with antiandrogens, and functionally they belong in the conversation, but they do not block the receptor. They reduce the supply of DHT. That difference shapes their side effect profile and why they are the drugs most often discussed for hair.
What does the evidence show for hair loss specifically?
For men with male pattern hair loss, oral finasteride 1 mg daily is licensed in the UK and has the most trial evidence of any oral option, typically showing reduced shedding and modest regrowth over twelve months in a majority of participants. Dutasteride is more potent against DHT but is not licensed for hair loss in the UK, so its use for that purpose is off label.
For women, the picture is different. Finasteride is not licensed for women, and evidence in postmenopausal women has been mixed. Spironolactone at doses commonly used in dermatology is frequently prescribed for female pattern hair loss and hirsutism, with supportive but lower quality evidence than the male data, and in the UK that is an off label use. Cyproterone acetate, usually as co-cyprindiol, is another option a specialist may consider.
In every case, topical minoxidil remains the licensed first line for pattern hair loss in both sexes, and it is common for a clinician to combine treatments. Realistic expectations matter: six to twelve months before judging, ongoing use to maintain any benefit, and better results the earlier treatment starts.
What are the side effects of antiandrogen therapy?
They vary enormously by drug, dose and the person taking it, which is exactly why prescriber oversight is not a formality. The list below is general, not exhaustive, and never a substitute for the patient information leaflet for your specific medicine.
- Common across the group: fatigue, hot flushes, reduced libido, mood changes, breast tenderness or enlargement in men, and weight change.
- Spironolactone: raised potassium, low blood pressure, irregular periods, breast tenderness. It is a diuretic as well as an antiandrogen, so kidney function and potassium are checked.
- Cyproterone acetate: liver effects, mood changes, blood clot risk in combined preparations, and a recognised meningioma risk with prolonged high dose use, which is why exposure is kept as short as clinically reasonable.
- Finasteride and dutasteride: sexual side effects including reduced libido and erectile difficulty in a minority. UK regulators have highlighted reports of psychiatric effects including depression and suicidal thoughts, and a patient alert card is now provided. Anyone experiencing mood changes on these medicines should contact their prescriber promptly.
- Non steroidal receptor blockers: liver toxicity is a recognised risk with some, particularly flutamide, which is why liver blood tests are monitored.
- Androgen deprivation in prostate cancer: bone density loss, metabolic and cardiovascular effects, and significant hot flushes, all managed as part of oncology care.
Pregnancy warning. 5-alpha-reductase inhibitors can harm a developing male fetus. Finasteride and dutasteride are contraindicated in pregnancy, and women who are or could become pregnant should not handle crushed or broken tablets. Spironolactone and cyproterone acetate also require contraception advice. If pregnancy is possible, raise it before the prescription is written, not after.
What monitoring does antiandrogen therapy involve?
Monitoring is part of the treatment. What gets checked depends on the drug, but the pattern is consistent: a baseline before starting, an early recheck, then periodic review.
| Medicine | Typically monitored | Why |
|---|---|---|
| Spironolactone | Potassium, kidney function, blood pressure | It is potassium sparing, so levels can rise, especially with other drugs |
| Cyproterone acetate | Liver function, mood, duration of use | Liver effects and cumulative dose related risks |
| Finasteride, dutasteride | Symptom review, mood, PSA interpretation in older men | These drugs roughly halve PSA, so results need adjusting |
| Bicalutamide, flutamide | Liver function tests | Recognised hepatotoxicity risk |
| Long term androgen deprivation | Bone density, lipids, glucose, cardiovascular risk | Low androgen states affect bone and metabolism |
The PSA point deserves emphasis. If you take finasteride or dutasteride and later have a prostate check, tell the clinician, because your PSA result needs interpreting differently.
Antiandrogens in gender affirming hormone therapy
In feminising hormone therapy, an antiandrogen is often prescribed alongside oestrogen to reduce androgen effects such as facial and body hair growth and androgen driven scalp hair loss. Spironolactone, cyproterone acetate and GnRH analogues are all used, and protocols differ between services and countries.
This is specialist prescribing with its own monitoring, and it should be managed by a gender identity service or an appropriately experienced clinician. Buying hormones or antiandrogens online without supervision carries real risks, including unmonitored potassium changes, liver effects, blood clot risk and products that are not what the label claims.
What else affects androgen driven hair loss?
Androgens are one factor among several, and a good assessment looks wider before anyone reaches for a prescription pad. Iron deficiency, thyroid disease, recent illness, rapid weight loss, medications and polycystic ovary syndrome all affect hair and are all treatable in their own right. Two conditions frequently sit alongside this topic: our guides to PCOS related hair loss and to treating menopause hair loss cover the overlap.
A useful first appointment usually includes a history, an examination of the scalp and pattern, and blood tests covering ferritin, full blood count and thyroid function, with hormone tests where the picture suggests them. The NHS overview of hair loss is a sensible starting point before an appointment.
Questions worth asking your prescriber
- Is this medicine licensed for my condition, or is it being used off label, and what does that mean for me?
- What is a realistic result, and when should we judge whether it is working?
- What happens if I stop, and is this a long term commitment?
- Which side effects should make me contact you straight away?
- What monitoring do I need, and how often?
- Does this interact with anything else I take, including supplements?
- What should I do about contraception or pregnancy plans?
- Are there alternatives, including topical options, worth trying first?
Where cosmetic hair care fits, and where it does not
It does not replace treatment, and it is important to be straight about that. Shampoos, conditioners and scalp serums are cosmetic products. They can make hair look and feel thicker, reduce breakage so length is retained, and keep the scalp comfortable. They do not block androgens, they do not alter follicle miniaturisation, and they are not an alternative to a prescription medicine for a medical condition.
Used alongside whatever your clinician recommends, gentle daily care is still worth having, particularly when hair is finer and more fragile. Grow Me® Hair Growth Shampoo is a sulfate free, vegan, UK made shampoo formulated with caffeine, biotin and rosemary for fuller looking hair. It is a cosmetic product only. Watermans has sold over 5 million bottles since 2012.
Frequently asked questions
What is antiandrogen therapy used for?
It is used for prostate cancer, androgenetic alopecia, hirsutism, hormonal acne and seborrhoea, polycystic ovary syndrome symptoms, and feminising gender affirming hormone therapy. The specific medicine and dose depend on the condition, and all of these treatments are prescription only.
Do antiandrogens regrow hair?
They can slow miniaturisation and produce partial regrowth in some people, most reliably when started early. They do not revive follicles that have been inactive for years, results take six to twelve months to judge, and any benefit is lost within months of stopping treatment.
Can women take antiandrogens for hair loss?
Yes, under medical supervision. Spironolactone is commonly prescribed in dermatology for female pattern hair loss and hirsutism, although in the UK this is off label. Finasteride is not licensed for women. Contraception is an important part of the discussion for anyone who could become pregnant.
Is spironolactone safe for long term use?
Many people take it for years with monitoring, but safety is individual. Potassium levels, kidney function and blood pressure are checked, and it interacts with several common medicines including ACE inhibitors and potassium supplements. Your prescriber decides the monitoring schedule.
What is the difference between finasteride and an antiandrogen?
Finasteride is a 5-alpha-reductase inhibitor, so it reduces conversion of testosterone into DHT rather than blocking the androgen receptor. True antiandrogens such as spironolactone or bicalutamide occupy the receptor. Both reduce androgen effect, but by different routes with different side effect profiles.
Can antiandrogens affect mood?
Mood changes are a recognised possibility across the group. UK regulators have highlighted reports of depression and suicidal thoughts with 5-alpha-reductase inhibitors, and a patient alert card is now provided. Anyone noticing low mood or distressing thoughts should contact their prescriber or NHS 111 without delay.
Are there natural alternatives to antiandrogen therapy?
Nothing available over the counter has been shown to match prescription antiandrogens, and supplements marketed as DHT blockers have weak evidence and can still interact with medicines. Treating iron deficiency, thyroid disease or PCOS where present is far more productive than a supplement aisle.
Should I stop antiandrogen therapy if I get side effects?
Contact your prescriber rather than stopping on your own, especially with medicines used in cancer care or gender affirming therapy, where stopping abruptly has consequences. Many side effects can be managed by adjusting the dose, timing or drug choice.
The bottom line
Antiandrogen therapy is genuinely effective for androgen driven conditions, and it is genuinely a medical decision. The right drug depends on your sex, your diagnosis, your other medicines, whether pregnancy is possible, and what you are willing to monitor. Anyone telling you a shampoo, a supplement or an online prescription without follow up is an equivalent option is not giving you the full picture.
If your hair is thinning, start with a GP or dermatologist, get the basics checked, and make the treatment decision with someone who can monitor it.
