Ancillary / Aromatase Inhibitor

Letrozole (Femara)

Most potent non-steroidal AI. Can suppress oestrogen to near zero. Powerful for gynaecomastia reversal but dangerous for routine oestrogen management.

Build protocol outline Open dose calculator TNHL ebooks

Educational reference only. This page does not diagnose, prescribe, or replace care from a licensed professional. Laws, availability, and clinical appropriateness vary by location.

Reference dose0.25–2.5 mg every other day (very careful titration)

Half-life48 hours

Risk flaghigh

Regulatory noteFDA-approved context noted

Side effects and watch-outs

⚠️ Very easy to crash oestrogen — highest crash risk of any AI
⚠️ Severe joint and bone pain with low E2
Bone density loss
Hot flushes
Libido loss
Depression from low E2
Fatigue
Cognitive impairment at very low E2
Use absolute minimum effective dose + bloodwork every 4 weeks