HormoneFDA ApprovedFDA Approved

Anastrozole

About

About Anastrozole

Anastrozole is an FDA-approved aromatase inhibitor used in TRT protocols to manage estradiol levels that become elevated during testosterone therapy. By blocking aromatase enzyme activity, it prevents excess conversion of testosterone to estradiol, mitigating estrogenic side effects such as gynecomastia and water retention. It is one of the most commonly prescribed ancillary medications in men's health and hormone optimization.

Science

Mechanism of Action

Competitively and selectively inhibits aromatase (CYP19A1) enzyme, blocking the conversion of androgens (testosterone, androstenedione) to estrogens (estradiol, estrone) in peripheral tissues including adipose, liver, and muscle.

Dosing

Typical Protocol

0.25–1 mg oral 1–3x per week alongside TRT; dose adjusted to maintain estradiol in optimal range (20–40 pg/mL).

⚠ Protocol information is for educational purposes only. Dosing must be determined by a licensed physician based on individual health status and goals.

Regulatory

Legal Status in 2026

FDA Approved

This compound has completed clinical trials and received formal FDA approval for one or more indications. It can be legally prescribed by licensed physicians, filled at any licensed pharmacy, and may be covered by insurance. Off-label use by physicians is also legal. This is the highest level of regulatory clearance available in the US.

Evidence

Evidence Tier

FDA Approved

Supported by the clinical trial data required for FDA approval, representing the highest evidence bar. Safety and efficacy have been established in multiple phases of human clinical trials.