Cyproterone Acetate
A potent steroidal anti-androgen and progestin. Widely used in transfeminine care (outside the US) to suppress testosterone, and for severe acne, hirsutism and prostate cancer. Effective but carries meningioma and hepatotoxicity concerns at higher cumulative doses.
01 Overview
Cyproterone acetate (CPA) blocks androgen receptors and suppresses gonadotropins, sharply lowering testosterone. In transfeminine hormone therapy it is a common anti-androgen in Europe and elsewhere (it is not FDA-approved in the US), typically at low doses. It also treats severe acne, hirsutism and, at high doses, prostate cancer.
Regulatory reviews have linked CPA to a dose-dependent risk of intracranial meningioma, prompting a shift to lower doses (often 10-25 mg/day) and limiting cumulative exposure. High doses can also be hepatotoxic, so liver monitoring is advised.
02 Mechanism
Competitive androgen-receptor antagonist with strong progestogenic activity that suppresses LH/FSH, cutting testosterone production and blocking peripheral androgen action.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Transfeminine T-suppression | 10–50 mg/day | Oral | Modern practice favours 10-25 mg/day to limit meningioma risk. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Testosterone suppressionStrongly lowers testosterone and blocks androgen action, aiding feminization. | toward castrate range | Clinical | |
| Reduced acne and hirsutismImproves androgen-driven skin and hair symptoms. | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| MeningiomaDose- and duration-dependent risk of intracranial meningioma. | Severe | Rare, dose-dependent | Clinical | |
| HepatotoxicityElevated liver enzymes and rare severe hepatotoxicity, mainly at high doses. | Severe | Rare (dose-related) | Clinical | |
| Venous thromboembolismCombined with estrogen in HRT, contributes to clotting risk. | Severe | Uncommon (with estrogen) | Observational |