항안드로겐 개요

Why Do You Need an Anti-Androgen?

For most transgender women, estradiol alone (especially at typical pill dosages) is insufficient to suppress testosterone (T) down into the target female range (< 50 ng/dL) ^[1] . Anti-androgens (T-blockers) are used in tandem with estradiol to either halt the production of testosterone or block it from bonding to your cellular receptors, thereby clearing the way for feminization ^[2] .

However, a critical caveat: Not everyone requires an anti-androgen. If you are utilizing a high-dose estradiol regimen (particularly injections) that successfully suppresses your T into the target range on its own, adding a T-blocker is biologically redundant and exposes you to unnecessary side effects ^[3] . This is known as “Monotherapy.”

The 4 Primary Anti-Androgens Compared

Medication	CPA (Androcur)	Spironolactone	Bicalutamide	GnRH Agonists
Generic Name	Cyproterone Acetate	Spironolactone	Bicalutamide	Leuprorelin / Goserelin
Mechanism	Progestin negative feedback loop (Halts T production)	Mild AR antagonist (Does not halt T production)	Potent AR antagonist (Does not halt T production)	Shuts down the HPG axis completely (Directly drops T to castrate levels)
Efficacy	Strong (Drops T to female range)	Weak (Blocks receptors, T stays high)	Does not drop T (T may even spike)	Absolute Strongest (Chemical castration)
Typical Dose	5-12.5 mg/day	50-200 mg/day	25-50 mg/day	Varies strictly by injection type
Administration	Oral	Oral	Oral	Subcutaneous / IM Injection
Primary Risks	Meningioma tumors (≥25mg) Liver toxicity / Depression	Hyperkalemia (Fatal Potassium Spikes) Low blood pressure	Liver toxicity Makes blood tests hard to read	Decreased bone density Injection site reactions
Guideline Status	Recommended by ES 2017 & WPATH SOC 8	Recommended by ES 2017 & WPATH SOC 8	NOT recommended for standard use	Strongly Recommended by guidelines
Global Access	Banned in the US. Common in EU/UK/Asia.	Standard in the US. Available globally.	Prescription required globally.	Extremely restricted due to price.

A Note on Guideline Evidence

CPA, Spironolactone, and GnRH Agonists are formally recommended by the two towering international authorities: Endocrine Society 2017 and WPATH SOC 8 ^{[1] [2]} . While Bicalutamide is heavily utilized in the DIY community due to its potency, it possesses a troubling lack of long-term data specifically studying transgender cohorts and is not recommended by these major guidelines for standard GAHT.

How to Choose

Your anti-androgen selection should be driven by your health baseline, regional availability, and budget ^[2] :

The Ideal Choice: GnRH Agonists (Puberty Blockers)

• Audience: Users with robust insurance coverage or access to national healthcare systems like the NHS.
• Advantage: Unbeatable efficacy. Flawlessly shuts down testosterone production with virtually zero organ toxicity.
• Drawback: Astoundingly expensive (often $500-$2000 USD out of pocket per dose) and requires injections.

The Reliable Standard (Outside the US): Low-Dose CPA

• Audience: The standard first-line choice across Europe, the UK, and Asia.
• Advantage: Extremely potent. Flattens testosterone dependably and cheaply.
• Drawback: Banned by the FDA in the United States over liver concerns. Doses above 12.5mg risk brain tumors (meningiomas).

The US Standard: Spironolactone

• Audience: The absolute default anti-androgen in the United States under informed consent clinics.
• Advantage: Readily legally available and incredibly cheap.
• Drawback: It is a diuretic (makes you pee constantly) and carries the lethal risk of Hyperkalemia (fatal potassium buildup). It also blocks receptors rather than halting T production, making blood tests tricky to interpret.

The Unorthodox Option: Bicalutamide

• Audience: Users who cannot tolerate Spiro or CPA, working strictly alongside an endocrinologist.
• Advantage: Incredibly powerful at blocking the androgen receptor. Preserves sexual function better than CPA.
• Drawback: Outright liver toxicity risks. Because it purely blocks receptors without lowering T production, your blood testosterone levels will actually skyrocket (even though the T can’t do anything). This makes it almost impossible to dose via standard blood work.

The Lethal Combo: CPA + Bicalutamide

You must never take CPA and Bicalutamide simultaneously. Both drugs inherently stress the hepatic system; combining them heavily magnifies your risk of chemically-induced liver failure ^[1] . If you are switching from one to the other, stop the first drug completely before initiating the second.

Detailed Pages

• CPA (Cyproterone Acetate) — The most common blocker globally; dosing limits and brain tumor risks.
• Spironolactone — The US standard; managing the deadly hyperkalemia risk.
• Bicalutamide — The rebel alternative; navigating the liver risks and blood test confusion.
• GnRH Agonists — The gold standard shut-down; price tags and bone density management.