At a glance
Effects
- Androgenic strength: Strong androgenic activity — promotes secondary male characteristics including facial/body hair, voice deepening, and libido [3].
- Muscle protein synthesis: Increases nitrogen retention and protein synthesis in muscle tissue, supporting lean mass and recovery [4].
- Erythropoiesis / O₂ delivery: Stimulates erythropoietic factor production, raising red blood cell counts and potentially improving muscular endurance [4].
- No aromatisation: The 9α-fluoro substitution prevents conversion to oestrogen, so estrogenic effects such as gynecomastia and fluid retention are not expected [5].
- Aggression / pre-competition drive: High androgenic potency is associated with pronounced increases in aggressive drive, historically exploited in combat sports and powerlifting [6].
Schedule III AAS (oral)
~9.2 hours
Oral (tablet)
17α-alkylated — HIGH
None (9α-fluoro blocks conversion)
About Fluoxymesterone
Every point here is drawn from public medical and harm-reduction sources. A bracketed number after a claim — like [1]— is a reference: tap it to open the exact source it's based on (numbered list at the bottom). It is not a rating or score. Educational information, not medical advice.
Product specifics
- Est. delivery
- 3–7 business days · EU tracked
Product details as stated by the vendor (claims, not independently verified). Delivery is our standard EU estimate.
What it is
Fluoxymesterone (brand name Halotestin) is a potent, orally active synthetic androgenic-anabolic steroid (AAS) and a 17α-alkylated derivative of testosterone, FDA-approved since 1957 [1]. It is used medically for male hypogonadism, delayed puberty, and palliative treatment of androgen-responsive breast cancer in women [2].
How it works
Fluoxymesterone binds to and activates androgen receptors (AR) in muscle, skin, reproductive tissue, and other organs, translocating to the nucleus to modulate gene expression [3]. This drives increased protein synthesis, nitrogen retention, and erythropoiesis (red blood cell stimulation) [4]. Its 9α-fluoro group prevents aromatisation to oestrogen while enhancing androgenic potency, and its 17α-methyl group resists first-pass hepatic metabolism, enabling oral activity [3][5]. It suppresses the hypothalamic-pituitary axis via negative feedback, reducing LH and FSH secretion [3].
Risks & side effects
Most important: Fluoxymesterone is one of the most hepatotoxic oral steroids available: its 17α-alkylation allows oral activity but places severe metabolic burden on the liver, and prolonged use has been associated with cholestatic jaundice, peliosis hepatis, and hepatocellular neoplasms [2][7]. Liver function tests must be monitored regularly during any course of use.
Common
Serious
- Cholestatic jaundice and hepatitis [2][7]
- Peliosis hepatis (blood-filled hepatic cysts) [2]
- Polycythemia (elevated haematocrit) [2]
- Dyslipidaemia: reduced HDL, elevated LDL — cardiovascular risk [8]
- Hypertension and adverse cardiovascular outcomes [6]
- Suppression of clotting factors II, V, VII, and X — bleeding risk with anticoagulants [2]
- Premature epiphyseal closure in adolescents [7]
- Hypercalcaemia (particularly with immobilisation or breast cancer) [8]
Safety & harm reduction
- Pregnancy or women who may become pregnant (teratogenic/virilising) [2]
- Known or suspected prostate or male breast carcinoma [2]
- Existing hepatic impairment or active liver disease [8]
- Uncontrolled or poorly controlled heart failure [8]
- Adolescents with open epiphyses (risk of premature bone-plate closure) [7]
- Hypercalcaemia associated with malignancy (risk of worsening) [8]
- Liver function tests (ALT, AST, bilirubin) — periodically throughout use [7]
- Haematocrit and haemoglobin — monitor for polycythemia [7]
- Lipid panel (HDL, LDL) — cardiovascular risk assessment [7]
- Blood pressure — monitor regularly given cardiovascular risk [6]
- PSA (prostate-specific antigen) in older males [2]
- Bone age X-rays every 6 months in prepubertal males [7]
- Oral anticoagulants (warfarin): androgens potentiate anticoagulant effect — clotting factor suppression means INR can rise significantly; dose adjustment required [7]
- Oxyphenbutazone: concurrent use may elevate serum oxyphenbutazone levels [9]
- Insulin/oral antidiabetics: androgens may alter glucose tolerance; monitor blood sugar [8]
- Hepatotoxic drugs: additive liver stress — avoid combining with other 17α-alkylated AAS or hepatotoxic agents [7]
- Liver support: consider TUDCA or NAC supplementation during any oral AAS course; avoid alcohol entirely [7]
- Post-cycle therapy (PCT): HPG axis suppression requires a structured PCT (e.g. SERM such as nolvadex/clomid) to restore endogenous testosterone after discontinuation [3]
- Keep cycles short: due to severe hepatotoxicity, off-label use should be limited in duration; many harm-reduction sources recommend no more than 4–6 weeks [7]
- Divide daily dose: due to the ~9.2 h half-life, splitting into 2–3 daily doses maintains more stable plasma levels [2]
Dosage context
Medical prescribing context only (not a personal recommendation): The FDA-approved Halotestin label states a daily dose of 5–20 mg for complete testosterone replacement in hypogonadal males, and 10–40 mg/day in divided doses for palliative breast cancer treatment [2][9]. Doses are titrated to individual response; priapism is noted as a sign of excessive dosage [9]. These are prescription ranges — non-medical use carries additional risks not reflected in clinical trial data.
Sources
- 1.DrugBank — Fluoxymesterone
- 2.DailyMed — Halotestin (Fluoxymesterone) Tablet Label
- 3.Biomedicus — Halotestin Side Effects & Pharmacology
- 4.NCATS Inxight Drugs — Fluoxymesterone
- 5.Wikipedia — Fluoxymesterone
- 6.INCHEM / IPCS — Fluoxymesterone PIM 902
- 7.DailyMed (XSL) — Halotestin Full Prescribing Information
- 8.Medicine.com — Fluoxymesterone Dosage & Warnings
- 9.RxList — Halotestin (Fluoxymesterone)
- 10.ChemicalBook — Fluoxymesterone 76-43-7
This information is provided for educational and harm-reduction purposes only. It is not medical advice. These substances can carry serious health risks; effects and safe use vary by individual. Consult a qualified healthcare professional before use. Legal status varies by country — it is your responsibility to know your local law. We do not encourage misuse.