Cyproterone Acetate: Uses, Dosage, Side Effects & Meningioma Risk

✓ Medically reviewed by  ·  Last reviewed: May 2026

Morgan Ellis

Pharmacy Researcher · 8 years experience

Pharmacy researcher with 8 years reviewing clinical drug information, generic formulation equivalence, and international pharmaceutical standards. Focuses on patient-facing accuracy in medication education.

What is cyproterone acetate?

Cyproterone acetate (CPA) is a synthetic steroid hormone with two main pharmacological actions:

• Anti-androgen activity — it binds the androgen receptor without activating it, blocking testosterone and dihydrotestosterone (DHT) from producing their normal effects.
• Progestogenic activity — it activates the progesterone receptor, which also suppresses luteinising hormone (LH) and indirectly reduces testicular and adrenal androgen production.

This dual mechanism makes it effective in many androgen-driven conditions, but it also explains why it influences so many systems of the body and why monitoring is important. On this site, cyproterone acetate is available in combination with ethinylestradiol as Diane 35, a contraceptive pill used for androgen-related skin and hair conditions in women.

First developed in the 1960s, CPA has been widely prescribed in Europe, Asia, Australia, and Canada for over fifty years. It has never received FDA approval in the United States, which is why US patients often encounter alternatives such as spironolactone or bicalutamide for equivalent clinical goals.

How cyproterone acetate works

To understand CPA’s effects, it helps to understand what androgens normally do. Testosterone and DHT bind to androgen receptors in tissues including the prostate, hair follicles, sebaceous glands, and brain, producing classically male effects — body hair growth, scalp hair loss in those predisposed, oily skin, acne, increased libido, and support of sexual function.

CPA interferes with this at two levels:

1. Receptor blockade. CPA sits in the androgen receptor and prevents natural androgens from activating it, so tissues behave as if androgen levels were much lower than they actually are.
2. Suppression of androgen production. Through its progestin-like action on the pituitary, CPA lowers LH. The testes (in men) and the ovaries and adrenals (in women) respond by producing less testosterone.

The combined effect is stronger than either action alone. Hirsutism (unwanted hair growth) and hormonal acne improve because androgen signalling at the hair follicle and sebaceous gland is dampened from both sides.

Approved and common uses

Hirsutism, acne, and androgen-driven skin conditions in women

This is the most common use worldwide. CPA is typically given as part of a combined oral contraceptive (COC) containing 2 mg CPA with 35 μg ethinylestradiol — branded as Diane 35, Dianette, or several international equivalents. The contraceptive component provides reliable birth control and cycle regulation; the CPA component addresses the androgen-driven symptoms.

Results take time to emerge. Most patients see meaningful improvement in acne within 3 months and in hirsutism within 6–9 months. Hair shedding from the scalp (female-pattern alopecia driven by androgens) can also improve with consistent use.

Polycystic ovary syndrome (PCOS)

In PCOS with prominent androgenic symptoms — acne, hirsutism, androgenic alopecia — CPA-containing COCs are a common first- or second-line pharmacological option, alongside lifestyle interventions. Metformin is added when insulin resistance is prominent; spironolactone is an alternative anti-androgen in the United States where CPA is unavailable.

Gender-affirming hormone therapy for transgender women

Alongside oestradiol, CPA is widely used in Europe, Canada, and Australia to suppress endogenous testosterone in transgender women. Doses used in this context have fallen substantially over the years — historically 50–100 mg daily, now typically 10–25 mg daily. The lower doses are increasingly favoured because they achieve adequate testosterone suppression while reducing the risk of side effects, particularly the meningioma concern (see below).

Paraphilic disorders and hypersexuality in men

CPA at 100–300 mg daily is occasionally prescribed in specialist forensic or psychiatric settings for men whose sexual behaviour is distressing to themselves or others. It reduces libido and sexual function more reliably than lower doses used for other purposes.

Advanced prostate cancer

At doses of 200–300 mg daily, CPA is a palliative option in metastatic, castration-resistant prostate cancer. It is also occasionally used short-term at the start of gonadotropin-releasing-hormone (GnRH) agonist therapy to prevent the initial testosterone flare those drugs cause.

Dosage by indication

Clinically, the trend across all non-oncological indications has been toward lower doses. Large observational studies have found that doses above 25 mg daily in gender-affirming therapy offer no additional testosterone-suppression benefit beyond 10 mg, while the side-effect profile scales with dose.

Common side effects

Frequency and intensity depend on the dose. At the 2 mg CPA dose used in contraceptive pills, side effects are usually mild. At the 25+ mg daily doses used in gender-affirming therapy or higher, side effects become more pronounced.

• Breakthrough bleeding or amenorrhoea (in women using CPA-containing COCs)
• Breast tenderness and enlargement — in both men and women. In men, prolonged high-dose use produces gynecomastia.
• Reduced libido and sexual function — intended in some indications, unwanted in others.
• Mood changes, particularly depression and emotional flattening.
• Weight gain — common at higher doses; modest at 2 mg doses.
• Fatigue — disproportionate to workload; often improves once dose is stabilised.
• Mild elevation of liver enzymes — usually asymptomatic, found on blood tests.
• Headaches, especially in the first weeks.
• Reversible infertility — sperm production drops in men and ovulation is suppressed in women using CPA-containing COCs.

Serious risks and monitoring

Venous thromboembolism (VTE)

CPA-containing combined contraceptive pills carry a VTE risk roughly 1.5–2 times that of levonorgestrel-based pills. This is on top of the baseline VTE risk of any combined contraceptive. Risk is meaningfully higher in women who smoke, are over 35, have known thrombophilia, or are immobilised after surgery or injury. For these patients, a progestin-only contraceptive or non-hormonal alternative is preferred.

Liver toxicity

High-dose CPA (above 100 mg daily) has been associated with hepatitis, including a small number of cases of fulminant liver failure. The risk at 2 mg contraceptive doses is extremely low. Liver enzymes should be checked at baseline and periodically in patients on higher doses.

Adrenal insufficiency on abrupt discontinuation

High-dose CPA suppresses the hypothalamic-pituitary-adrenal axis. Stopping suddenly from doses above 100 mg daily can unmask adrenal insufficiency. If discontinuing, tapering over weeks and checking morning cortisol is standard.

Cardiovascular effects

CPA can lower HDL cholesterol and mildly raise LDL at higher doses, and combined CPA-estrogen therapy increases cardiovascular event rates compared with progestin-only options.

The meningioma warning

Practical implications:

• At the 2 mg dose in combined contraceptive pills, cumulative exposure rarely reaches the 10 g threshold even over years. Risk remains low.
• At 25–50 mg daily for gender-affirming use, the 10 g cumulative threshold is reached within 6–12 months, making cumulative dose a real consideration.
• Any new neurological symptom — persistent headache, vision change, limb weakness, personality change, new seizures — in a long-term CPA user warrants imaging.
• Periodic MRI is not routinely recommended at contraceptive doses but may be considered for patients on long-term high-dose therapy.

Who should not take cyproterone acetate?

• Known or suspected pregnancy
• Active or prior meningioma
• Significant liver disease or abnormal liver enzymes at baseline
• Active or prior venous thromboembolism
• Certain hormone-sensitive tumours (other than prostate cancer, where it may be indicated)
• Uncontrolled hypertension or significant cardiovascular disease (for CPA-EE contraceptive combinations)
• Severe diabetes with vascular complications
• Known hypersensitivity to cyproterone acetate

Combined CPA-EE contraceptives additionally carry all the standard estrogen-containing contraceptive contraindications — migraine with aura, smoking over 35, known thrombophilia.

Alternatives by indication

Frequently asked questions

Is cyproterone acetate the same as cyproterone?

Effectively yes — all clinical preparations use the acetate ester, which is absorbed orally and converted to the active compound. “Cyproterone” is commonly used as shorthand for “cyproterone acetate”.

Does cyproterone acetate stop your period?

At contraceptive doses (2 mg in Diane 35 and similar), monthly withdrawal bleeds are usually maintained. At higher doses (25+ mg), used alone without estrogen, periods typically stop within a few months.

How long does it take to work for hirsutism?

Meaningful reduction in unwanted hair growth takes 6–9 months. Hair follicle cycles are slow, and existing hairs must shed naturally before reduced replacements become visible. Acne usually responds within 3 months.

Can men take cyproterone acetate?

Yes — it is used in men for prostate cancer, paraphilic disorders, and certain forms of hypersexuality. At non-cancer doses, it suppresses testosterone and libido and can cause breast tissue development.

Is cyproterone acetate legal in the US?

Cyproterone acetate is not FDA-approved and is not available through standard US prescription channels. US patients and clinicians typically substitute spironolactone or bicalutamide for equivalent anti-androgen effects.

Does CPA cause weight gain?

At contraceptive doses, weight effects are minimal for most users. At higher doses used for gender-affirming therapy or prostate cancer, modest weight gain is common — partly from redistribution of body fat under hormonal changes and partly from reduced basal metabolism.

Is the meningioma risk permanent?

Meningiomas that develop under CPA exposure sometimes regress after the drug is stopped, though not reliably. Existing meningiomas are a contraindication to continued use. Any new neurological symptoms warrant prompt imaging.

Can CPA cause infertility?

Yes — reversibly, in both men and women. Sperm production drops substantially under high doses; ovulation is suppressed in women on CPA-containing contraceptives. Fertility typically returns within weeks to months after stopping.

What happens if I miss a dose?

For the CPA-EE contraceptive, the missed-pill rules are the same as other combined oral contraceptives. For higher-dose monotherapy, take the missed dose as soon as you remember unless it is close to the next scheduled dose; do not double doses.

Do I need regular blood tests on cyproterone acetate?

Yes for higher doses. Monitoring typically includes liver function tests, fasting lipids, full blood count, and hormone levels (testosterone for gender-affirming therapy or prostate cancer). Contraceptive-dose users follow standard COC monitoring (BP, periodic review).

Written by

Sophie Chen

Pharmaceutical Content Researcher · 8 years experience

Sophie Chen is a pharmaceutical content researcher with 8 years covering generic medication access and clinical pharmacology. She specialises in international regulatory frameworks, bioequivalence standards, and patient-facing education on therapeutic drug classes. She is not a clinician.