Ancillary / DHT Blocker

Finasteride (Propecia)

5-alpha reductase inhibitor. FDA-approved for hair loss and BPH. Reduces DHT by ~70%. Used to prevent hair loss on TRT/AAS cycles. ⚠️ Post-Finasteride Syndrome controversially reported.

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 doseHair loss: 1 mg/day. BPH: 5 mg/day

Half-life8 hours

Risk flagmoderate

Regulatory noteFDA-approved context noted

Side effects and watch-outs

Sexual side effects: reduced libido, erectile dysfunction, ejaculatory dysfunction
⚠️ Post-Finasteride Syndrome — persistent sexual/cognitive/mood side effects after discontinuation (controversial — possibly permanent in some users)
Gynaecomastia (DHT reduction allows oestrogen dominance)
Depression
Rare: liver injury
⚠️ Increases cancer detection risk on PSA test — affects PSA levels