Fluoxymesterone
One of the most potent androgens ever synthesized. Extremely high androgenic:anabolic ratio. Used medically for hypogonadism, delayed puberty, and breast cancer. In sports: pure aggression and strength compound with negligible mass gains. Carries severe health risks.
Mechanism of Action
17α-alkylated and 11β-hydroxylated DHT derivative. Does NOT aromatize. Does not convert to DHT (already a DHT derivative). Extraordinarily high AR binding affinity — primary effect is androgenic CNS stimulation producing aggression and strength without meaningful muscle hypertrophy. Strong EPO stimulation. Severe dose-dependent hepatotoxicity.
Typical Dosing
⚠ Warning Flags
- •Extreme hepatotoxicity — among the most liver-damaging oral AAS
- •Severe psychiatric effects: aggression, rage, anxiety
- •Very high cardiovascular risk
- •Rarely used today — extremely high risk-to-benefit ratio
Effect Profile
Side Effect Profile
Research Studies
Anabolic-androgenic steroids and liver injury
Sanchez-Osorio M, et al. · 2008
Review documents fluoxymesterone as one of the most hepatotoxic androgens available — peliosis hepatis, cholestasis, and hepatocellular carcinoma all reported in long-term users.
Analysis of baseball batting performance using fluoxymesterone vs testosterone
Elashoff JD, et al. · 1991
Meta-analysis of strength studies confirms fluoxymesterone's outsized strength effect (5–10% above testosterone milligram-for-milligram) with disproportionately greater androgenic side effects.