hormoneControlledSchedule III (US, Anabolic Steroids Control Act)Prescription only (US)FDA-approved (Halotestin) for hypogonadism, delayed puberty, and metastatic breast cancerAlso scheduled as a prohibited anabolic androgenic steroid by WADA
FluoxymesteroneBenefits, Dosage & Interactions
Also known as: Halotestin
Fluoxymesterone, sold under the brand name Halotestin, is an androgenic anabolic steroid (AAS) that belongs to the 17-alpha-alkylated class of testosterone derivatives. Research on Fluoxymesterone focuses on testosterone support. Fluoxymesterone is a controlled substance in some jurisdictions. Dose, response, and interaction risk vary by individual, so use should be reviewed with a clinician.
How much Fluoxymesterone do people take?
Breast cancer trials used 10 mg orally three times daily (30 mg/day); early androgen-replacement reports used 5–20 mg/day. Route reported: Oral tablets in every cited study. Frequency reported: Two to three times daily in the breast cancer trials. These are amounts documented in the cited studies and labels for Fluoxymesterone — they are reported for reference, not a recommendation. Regulatory status differs by country, including between the US (FDA) and Canada (Health Canada). Confirm any amount with a licensed clinician before you take it.
See the full reported protocol and its sourcesResearched by DoseRoutine Research TeamReviewed for accuracy by Nicholas Alexander, RSE, SO, PMPLast updated Educational reference only — not medical advice. Always confirm dosing and safety decisions with a licensed clinician.
Evidence: Strong — 2 human randomized trials and regulatory approval on file.
Evidence strengthStrong · 4/4
PreclinicalStrong human evidence
2 human randomized trials and regulatory approval on file.
Plasma half-life
Approximately 9.2 hours
Default unit
mg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
- Reported amounts
- Breast cancer trials used 10 mg orally three times daily (30 mg/day); early androgen-replacement reports used 5–20 mg/day[1][2][3]
Reported for Fluoxymesterone in the cited sources. Published ranges are not dosing advice.
Fluoxymesterone compared with similar compounds
| Attribute | Testosterone Cypionate | Oxandrolone |
|---|---|---|
| Class | Injectable testosterone ester | Oral 17α-alkylated anabolic steroid |
| Route | Intramuscular injection | Oral tablets |
| Half-life | ~8 days | ~9–10 hours |
| Evidence grade | Strong | Strong |
| Oral stability | Not orally bioavailable (ester form) | Orally bioavailable (17α-alkylated) |
| Typical published cycle | Weekly to biweekly injections, ongoing in replacement therapy | 2–4 weeks in burn and wasting trials |
| Main studied use | Male hypogonadism / testosterone replacement | Weight restoration in catabolic states |
References & evidence
Documents the Fluoxymesterone entry is written from. Each number matches an inline marker above.
- [1]Tamoxifen and fluoxymesterone in advanced breast cancer: a controlled clinical trialWesterberg H · Cancer Treatment Reports · 1980 · Peer-reviewed · PMID 6991101
- [2]Randomized trial of tamoxifen alone or combined with fluoxymesterone as adjuvant therapy in postmenopausal women with resected estrogen receptor positive breast cancer. North Central Cancer Treatment Group Trial 89-30-52Ingle JN, Suman VJ, Mailliard JA, et al. · Breast Cancer Research and Treatment · 2006 · Peer-reviewed · PMID 16538529
- [3]Fluoxymesterone; a new oral androgenBuckle RM · British Medical Journal · 1959 · Peer-reviewed · PMID 13651739
References & Evidence
Sources on this page that document Fluoxymesterone dosing, timing and safety.
- [1]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is Fluoxymesterone studied for?
What is Fluoxymesterone?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
Fluoxymesterone, sold under the brand name Halotestin, is an androgenic anabolic steroid (AAS) that belongs to the 17-alpha-alkylated class of testosterone derivatives. It is primarily used in men for conditions associated with a deficiency or absence of endogenous testosterone, such as primary hypogonadism and hypogonadotropic hypogonadism. In limited clinical settings, it has also been approved for use in women with inoperable breast cancer for palliative treatment. As a controlled substance, its medical use is tightly regulated and requires a prescription. Fluoxymesterone is known for its strong androgenic properties and moderate anabolic effects, making it distinct from many other anabolic steroids which might have a higher anabolic to androgenic ratio. Due to its hepatotoxicity and a high potential for side effects, its therapeutic applications are very specific and limited. It is administered orally.
What does the research say about Fluoxymesterone?
Tap a section to expand.
Fluoxymesterone exerts its effects by binding to androgen receptors (ARs) located in various tissues throughout the body, including muscle and bone cells. Upon binding, the fluoxymesterone-receptor complex is translocated into the cell nucleus, where it interacts with specific DNA sequences (androgen response elements) to modulate gene transcription. This leads to an increase in protein synthesis, which is the basis for its anabolic effects, and also contributes to its androgenic effects such as the development and maintenance of male secondary sexual characteristics. Unlike some other anabolic steroids, fluoxymesterone is not extensively aromatized into estrogen, meaning it has a lower propensity to cause estrogenic side effects. Its 17-alpha-alkylation significantly reduces its hepatic metabolism when taken orally, increasing its oral bioavailability but also contributing to its hepatotoxicity. (DrugBank, FDA label)
Source for this section: Sources for How does Fluoxymesterone work?: Jumps to this entry in the sources and references list at the end of the page.
Fluoxymesterone's approved medical benefits are primarily focused on testosterone replacement therapy in males and palliative treatment for specific breast cancers in females.
* **Male Hypogonadism:** For men with conditions such as primary hypogonadism (testicular failure due to cryptorchidism, bilateral torsion, orchitis, vanishing testis syndrome, or orchidectomy) or hypogonadotropic hypogonadism (gonadotropin or LHRH deficiency, pituitary-hypothalamic injury from tumors, trauma, or radiation), fluoxymesterone can be prescribed to replace endogenous testosterone. This can help to restore secondary sexual characteristics, improve bone mineral density, and address symptoms like low libido, fatigue, and muscle weakness associated with low testosterone levels. (FDA label)
* **Palliative Treatment of Inoperable Breast Cancer in Women:** In selected cases, fluoxymesterone is used as a palliative treatment for women with advanced, inoperable metastatic breast cancer. Its anti-estrogenic effects, possibly through blockade of estrogen receptors or interference with estrogen synthesis, can slow the progression of hormone-sensitive tumors. This use is rare and considered when other treatments are not suitable or have failed. (FDA label)
Clinical evidence for fluoxymesterone is primarily based on studies supporting its use for testosterone replacement and palliative breast cancer treatment. Its efficacy in managing symptoms of hypogonadism, such as improving libido, muscle mass, and bone density in men with testosterone deficiency, is established through clinical trials supporting its FDA approval for these indications. For breast cancer, studies have demonstrated its utility in selected advanced cases, showing responses such as tumor regression or stabilization, though its use has become less common with the advent of more targeted therapies. The exact methodologies and results are detailed in its regulatory approval documents. (FDA label)
Fluoxymesterone, like other anabolic steroids, can cause a range of side effects due to its potent androgenic and anabolic activity. These effects can vary in severity and depend on the individual's physiology, dosage, and duration of use. Common side effects include:
* **Androgenic Effects:** Acne, oily skin, male pattern baldness (in genetically predisposed individuals), hirsutism (excessive hair growth) in women, deepening of the voice in women, clitoral enlargement in women, and priapism (prolonged erection) in men.
* **Cardiovascular Effects:** Adverse changes in lipid profiles (decreased HDL-C and increased LDL-C), increased blood pressure, and increased risk of cardiovascular events.
* **Hepatic Effects:** Liver dysfunction, including elevated liver enzymes, cholestatic jaundice, peliosis hepatis (blood-filled cysts in the liver), and hepatic neoplasms (tumors), especially with prolonged use. This is a significant concern due to its 17-alpha-alkylated structure.
* **Endocrine Effects:** Suppression of endogenous testosterone production in males, testicular atrophy, impaired spermatogenesis, gynecomastia (breast enlargement in men) (though less common due to low aromatization), menstrual irregularities in women.
* **Psychological Effects:** Mood swings, aggression, irritability, depression. This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Fluoxymesterone carries several significant warnings due to its potent pharmacological effects and potential for severe adverse reactions:
* **Hepatotoxicity:** Oral 17-alpha-alkylated androgens, including fluoxymesterone, are known to be hepatotoxic. Liver function tests should be monitored regularly during therapy, and treatment should be discontinued if cholestatic jaundice or other signs of liver damage appear. Peliosis hepatis and hepatic neoplasms, sometimes life-threatening, have been reported.
* **Cardiovascular Risk:** Anabolic steroids can alter lipid profiles, increasing the risk of atherosclerosis, coronary artery disease, and stroke. Patients with pre-existing cardiovascular conditions or risk factors should be closely monitored.
* **Prostatic Carcinoma:** Androgens may accelerate the growth of existing prostatic carcinoma and benign prostatic hyperplasia. Regular prostate evaluations (including PSA levels) are essential in men receiving fluoxymesterone.
* **Fluid and Electrolyte Imbalance:** Androgens can cause sodium and water retention, leading to edema. Caution is advised in patients with cardiac, renal, or hepatic disease.
* **Virilization in Females:** Women using fluoxymesterone may experience permanent virilizing changes, including deepening of the voice, clitoral enlargement, and hirsutism. Careful consideration of benefits vs. risks is required.
* **Abuse Potential:** Fluoxymesterone is a controlled substance with a high potential for abuse, leading to psychological dependence and significant health risks. This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Fluoxymesterone is contraindicated in several situations where its use could pose significant health risks:
* **Known or suspected carcinoma of the prostate or breast in males:** Androgens can stimulate the growth of these hormone-sensitive cancers.
* **Breast cancer in females with hypercalcemia:** Anabolic steroids may increase serum calcium levels by stimulating osteolysis. If hypercalcemia occurs, the drug should be discontinued.
* **Pregnancy and lactation:** Fluoxymesterone can cause fetal harm when administered to a pregnant woman and is contraindicated during pregnancy. It is unknown whether it is excreted in human milk, but due to potential adverse effects on the nursing infant, it should not be used during lactation.
* **Nephrosis or the nephrotic phase of nephritis:** Due to the risk of fluid retention.
* **Hypersensitivity:** To fluoxymesterone or any components of its formulation.
* **Severe liver impairment:** Due to its significant hepatotoxicity. This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Combining fluoxymesterone with certain medications can lead to adverse interactions or increased risk of side effects:
* **Anticoagulants (e.g., Warfarin):** Anabolic steroids can increase the anticoagulant activity of coumarin-type anticoagulants, potentially leading to increased bleeding risk. Close monitoring of INR/PT is necessary.
* **Corticosteroids and ACTH:** Concomitant administration may increase the risk of edema.
* **Insulin and Oral Hypoglycemic Agents:** Anabolic steroids may alter glucose tolerance and requirements for these agents. Dose adjustments may be necessary for diabetic patients.
* **Other Hepatotoxic Agents:** Concurrent use with other drugs known to be hepatotoxic should be avoided or approached with extreme caution, due to the additive risk of liver damage.
* **Thyroid Hormones:** Anabolic steroids may decrease serum levels of thyroid-binding globulin, resulting in decreased total T4 serum levels and increased resin uptake of T3 and T4. Free thyroid hormone levels generally remain unchanged. This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Fluoxymesterone can be taken at any time of day, as directed by a licensed clinician. It can be taken either with or without food. The user's specific dose and timing regimen must be set by a licensed clinician.
Source for this section: Sources for When should you take Fluoxymesterone?: Jumps to this entry in the sources and references list at the end of the page.
Put it into practice
Reading about Fluoxymesterone is the first step — DoseRoutine helps you act on it. These free tools turn what you just learned into a routine.
What interacts with Fluoxymesterone?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Any peptide + hormone | Note | Category ruleConfidence: theoretical | Injectable peptides plus hormones can have overlapping or compounding effects that aren't always well characterized.Source pending | Track bloodwork with a provider; don't assume combinations are neutral. |
Frequently asked questions about Fluoxymesterone
Fluoxymesterone is a hormone. It is also known as Halotestin. The references summarized come from NIH and PubMed records, FDA labeling where it exists, and Mayo Clinic patient material.
Fluoxymesterone is commonly discussed in the context of supporting testosterone. Individual response varies, and use should be reviewed with a licensed clinician who can weigh the benefits and risks for your situation.
For Fluoxymesterone, it is typically taken null. Always follow the specific dose your clinician or the product label prescribes.
Fluoxymesterone carries potential side effects and drug interactions, documented in NIH, Mayo Clinic, and FDA label sources. Fluoxymesterone is classified as a controlled substance in some jurisdictions, so legal status and prescribing rules apply. Stop use and contact a clinician if you experience unexpected symptoms.
As a hormone, Fluoxymesterone can overlap with other supplements, prescription medicines, hormones and peptides. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers Fluoxymesterone with no sign-up.
Whether Fluoxymesterone fits alongside testosterone replacement therapy depends on the protocol — dose, ester and ancillaries such as HCG or anastrozole — and on current bloodwork. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
"Peptides" is not one category — healing peptides, GLP-1 agonists, growth-hormone secretagogues and melanocortins each behave differently next to Fluoxymesterone. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
Published frequency for Fluoxymesterone varies by protocol and formulation, so the label or prescription is what sets it. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
The effect of a missed dose of Fluoxymesterone depends on the protocol and formulation you are on. Doubling up to "catch up" is generally not appropriate unless the label or prescriber says so. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For Fluoxymesterone the useful record is the dose, the time it was actually taken, and what else was taken in the same window. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
Breast cancer trials used 10 mg orally three times daily (30 mg/day); early androgen-replacement reports used 5–20 mg/day. Route reported: Oral tablets in every cited study. Frequency reported: Two to three times daily in the breast cancer trials. These are amounts documented in the cited studies and labels for Fluoxymesterone — they are reported for reference, not a recommendation. Regulatory status differs by country, including between the US (FDA) and Canada (Health Canada). Confirm any amount with a licensed clinician before you take it.
Which studies looked at Fluoxymesterone?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.Tamoxifen and fluoxymesterone versus tamoxifen and danazol in metastatic breast cancer--a randomized study(opens PubMed in a new tab)Breast Cancer Res Treat · 1988 · PMID 3058238 · https://pubmed.ncbi.nlm.nih.gov/3058238/
- 2.Randomized comparison of megestrol acetate versus dexamethasone versus fluoxymesterone for the treatment of cancer anorexia/cachexia(opens PubMed in a new tab)J Clin Oncol · 1999 · PMID 10506633 · https://pubmed.ncbi.nlm.nih.gov/10506633/
- 3.Evaluation of tamoxifen doses with and without fluoxymesterone in advanced breast cancer(opens PubMed in a new tab)Ann Intern Med · 1983 · PMID 6824247 · https://pubmed.ncbi.nlm.nih.gov/6824247/
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- PubChem CID 6446(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/6446
Verify at
Publisher search links for Fluoxymesterone. These are places to check the information — they are not citations, so they are not numbered.
- DrugBank(publisher search, opens in a new tab)DrugBank Online · publisher search
- FDA-approved labeling (DailyMed)(publisher search, opens in a new tab)U.S. Food and Drug Administration · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on Fluoxymesterone?
Plain-text summary, safe to quote verbatim:
Fluoxymesterone, sold under the brand name Halotestin, is an androgenic anabolic steroid (AAS) that belongs to the 17-alpha-alkylated class of testosterone derivatives. Research on Fluoxymesterone focuses on testosterone support. Fluoxymesterone is a controlled substance in some jurisdictions. Dose, response, and interaction risk vary by individual, so use should be reviewed with a clinician.
Source: DoseRoutine — https://doseroutine.com/library/fluoxymesterone
Fluoxymesterone cheat sheet
DoseRoutine cheat sheet · Hormone
Fluoxymesterone
Fluoxymesterone, sold under the brand name Halotestin, is an androgenic anabolic steroid (AAS) that belongs to the 17-alpha-alkylated class of testosterone derivatives.
Evidence
Strong
2 human randomized trials and regulatory approval on file.
Studied range
Breast cancer trials used 10 mg orally three times daily (30 mg/day); early androgen-replacement reports used 5–20 mg/day
Route
Oral tablets in every cited study
Frequency studied
Two to three times daily in the breast cancer trials
Half-life
Approximately 9.2 hours
Storage
Room temperature, sealed, away from moisture
Schedule III (US, Anabolic Steroids Control Act)Prescription only (US)FDA-approved (Halotestin) for hypogonadism, delayed puberty, and metastatic breast cancerAlso scheduled as a prohibited anabolic androgenic steroid by WADATestosterone
Key references
- Tamoxifen and fluoxymesterone in advanced breast cancer: a controlled clinical trial (1980)
- Randomized trial of tamoxifen alone or combined with fluoxymesterone as adjuvant therapy in postmenopausal women with resected estrogen receptor positive breast cancer. North Central Cancer Treatment Group Trial 89-30-52 (2006)
- Fluoxymesterone; a new oral androgen (1959)
Studied ranges, not dosing advice. Not medical advice — talk to a clinician. doseroutine.com/library/fluoxymesterone
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). Fluoxymesterone — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/fluoxymesterone
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