Halotestin (Fluoxymesterone)
Fluoxymesterone, 9α-fluoro-11β-hydroxy-17α-methyl-testosterone-derivative oral AAS. Originally FDA-approved (Halotestin, Upjohn 1957). The highest androgenic activity among AAS – boxing/powerlifting pre-competition "strength-amplifier" use with MINIMAL muscle mass building.
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WHAT IS HALOTESTIN (FLUOXYMESTERONE)?
Detailed overview
Halotestin (Fluoxymesterone) is a 9α-fluoro-11β-hydroxy-17α-methyl-testosterone-derivative oral AAS synthesized by Upjohn in 1956, FDA-approved in 1957 for delayed puberty, male hypogonadism and (formerly) breast cancer. Withdrawn from the US market in 1992, Pfizer generic still available on some EU markets. Anabolic:androgenic ratio ~1900:850 (extreme – the highest androgenic activity among AAS). The 9α-fluoro + 11β-OH steric blocking prevents aromatization + glucocorticoid receptor (GR) agonist activity (hence the "drying" effect and spiky aggression). 17α-methyl group → HIGH hepatotoxicity. NOT a standard bodybuilding use (NOT a bulker, NOT good for cutting); specifically a boxing, powerlifting, strongman pre-competition "strength + aggression amplifier" with 5-10% 1RM elevation in 1-3 weeks and minimal actual muscle mass gain. Roy Jones Jr. (2003 Boxing News doping scandal) and many other boxers have tested positive for Halotestin. WADA-banned year-round.
Mechanism
AR + GR agonist, 9α-fluoro, NOT aromatized
Anabolic:Androgenic
1900:850
Half-life
9 hours (oral)
Onset
1-2 h (oral)
Legal status
USA discontinued 1992, Pfizer generic EU, Schedule III
Data console
Lab data
Safety
Side effects, stop signs, contraindications
Side effects · 7
- Severe hepatotoxicity: due to the 17α-methyl group, 3-7x ALT/AST elevation, cholestatic jaundice, rarely peliosis hepatis and hepatic tumors – Halotestin is among the most toxic oral AAS.
- Drastic lipid deterioration: HDL drop of up to 40-50% within weeks, LDL rise – substantially increased risk of atherosclerosis and cardiovascular events.
- Marked psychiatric effects ("Halo-rage"): intense aggression, irritability, mood swings, sleep disturbance – Halotestin is among the most psychotropic AAS, with documented behavioral changes.
- Strong androgenic side effects: oily skin, acne, androgenic hair loss (accelerated in predisposed men), prostate stimulation – more pronounced than most AAS due to extreme androgenic activity (1900:850).
- HPTA suppression: inhibition of endogenous testosterone production and spermatogenesis, testicular atrophy, libido fluctuation, post-cycle hypogonadism without PCT.
- Elevated blood pressure (often above 140/90), partly from sodium retention and cardiovascular strain.
- In women, rapid and often irreversible virilization: deepening voice, facial hair, clitoral enlargement, menstrual disruption – especially dangerous due to extreme androgenic activity.
Contraindications · 7
- Any existing liver disease or elevated liver enzymes: absolute contraindication due to pronounced 17α-alkylated hepatotoxicity.
- Psychiatric predisposition (depression, bipolar disorder, anxiety, aggression-control disorders): absolutely contraindicated due to "Halo-rage".
- Cardiovascular disease or high risk (hypertension, high LDL, family history): contraindicated due to drastic HDL drop and blood pressure rise.
- Pregnancy and breastfeeding: teratogenic, causes fetal virilization – absolute contraindication.
- Women and adolescents: extreme androgenic activity causes rapid, irreversible virilization and premature growth-plate closure.
- Prostate or male breast carcinoma, or known prostatic hypertrophy: contraindicated due to androgenic stimulation.
- Concurrent hepatotoxic load (alcohol, paracetamol, NSAIDs, other 17α-alkylated oral AAS): contraindicated due to cumulative liver damage.
Related Performance Compounds
Same therapeutic category
Studies
Related research and clinical findings
Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement
Pope HG Jr, Wood RI, Rogol A, Nyberg F, Bowers L, Bhasin S.
Effects of androgenic-anabolic steroids in athletes
Hartgens F, Kuipers H.
Metabolism of anabolic androgenic steroids
Schänzer W.
Anabolic-androgenic steroid abuse and performance-enhancing drugs among adolescents
Bahrke MS, Yesalis CE, Brower KJ.
Anabolic-androgenic steroid dependence: an emerging disorder
Kanayama G, Brower KJ, Wood RI, Hudson JI, Pope HG Jr.
Telegram
Have a question about Halotestin (Fluoxymesterone)?
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The information here is for educational and scientific purposes only. Performance-enhancing compounds (AAS, prohormones, stimulants, doping agents) are illegal without prescription in Hungary and most of the EU, and carry serious health and legal risks. WADA bans them in competitive sport. This is NOT a usage guide, and we do not encourage any illegal use. If you do use them, medical supervision and regular bloodwork are ESSENTIAL. Severe endocrine, cardiovascular, hepatic and psychiatric side effects are possible.