Anastrozole (Anastrozole (Arimidex))
An aromatase inhibitor widely prescribed by telemedicine clinics alongside testosterone therapy to control estrogen conversion. Prevents testosterone from being converted to estradiol, maintaining hormonal balance.
How it works
Selectively and reversibly inhibits aromatase (CYP19A1), the enzyme that converts androgens to estrogens. Reduces circulating estradiol levels without affecting other steroid pathways.
Key facts
- Molecular weight: 293.37 Da
- Half-life: ~46.8 hours
- Bioavailability: ~80-85% oral
- Storage: Room temperature.
Dosing overview
- Typical dose: 0.25-0.5 mg
- Frequency: 2-3x per week
- Duration: As long as on TRT/hormone therapy
- Route: Oral tablet
Protocol notes
- Used alongside TRT to control estrogen - a common starting point is 0.25 mg twice weekly.
- Adjust the dose/frequency strictly by estradiol bloodwork, not by feel.
- Many men on properly-dosed TRT need little or no AI - only add it if estradiol is genuinely high with symptoms.
Reported benefits
- Estrogen control
- Reduced water retention
- Prevention of gynecomastia
- Maintained testosterone ratio
- Improved body composition
Possible side effects
- Joint pain/stiffness
- Bone density loss (long-term)
- Fatigue
- Hot flashes
- Mood changes
- Crashed estrogen (overdose)
Research
- Low-dose anastrozole in male hormone optimization (2022): Twice-weekly 0.25mg maintained estradiol in optimal range (20-30 pg/mL) without joint side effects in men on TRT.
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Community discussions about Anastrozole
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Research and educational reference only. Not medical advice.