We use essential cookies (authentication, your saved goals/stack) by default. With your permission we’ll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Methenolone (Primobolan) — a mild anabolic-androgenic steroid; injectable enanthate (Primobolan Depot) / oral acetate; DEA Schedule III controlled substance
A mild anabolic-androgenic steroid (AAS) — brand Primobolan — sold as an injectable enanthate ester (Primobolan Depot) and an oral acetate tablet, and a DEA Schedule III CONTROLLED SUBSTANCE. It is a derivative of dihydrotestosterone (DHT), so it is non-aromatizable (cannot convert to estradiol) and only weakly androgenic and weakly anabolic relative to testosterone. Its real clinical history is OLD and THIN: it was used decades ago to raise hemoglobin in bone-marrow-failure anemias (myelofibrosis, aplastic anemia, MDS) and, historically, as a palliative hormonal agent in advanced breast cancer — evidence that is mostly retrospective series and case reports, not modern RCTs. Off-label it is used in bodybuilding for lean-mass retention while dieting. The honest counterweight: it is NOT a dietary supplement and NOT a longevity drug; non-medical use is unsupervised; and as an AAS it still suppresses the hypothalamic-pituitary-testicular axis, shifts lipids unfavourably, and can virilize. Methenolone acetate is a 1-methyl steroid with a 17β-acetate ester; it is not 17α-alkylated. Anabolic steroids as a class have been associated with serious liver injury, peliosis and liver tumours. This class evidence does not quantify the risk of each methenolone form or establish that an injectable form is safe for the liver. Described for harm-reduction information only — not a recommendation.
Prescription medication — not a dietary supplement
Methenolone (Primobolan) is a prescription (or investigational) drug, not a supplement. It is included here for reference because people research and discuss it (often used off-label) — not as a recommendation. Take it only under a qualified clinician's supervision and only as prescribed; do not source it from grey-market vendors, where identity, purity, and dosing are unverified. The evidence below reflects its clinical trials.
What the evidence says
Most Methenolone (Primobolan) studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality randomised trials published 1968–2024 with a typical study size of 39 participants.
Based on 7 studies · 2 RCTs · 111 total participants
Confidence
Low confidenceBy outcome
Methenolone (Primobolan) is a real, well-characterized but MILD anabolic-androgenic steroid (a non-aromatizable DHT derivative). Its genuine clinical evidence is OLD and THIN: it was used for decades to raise hemoglobin in bone-marrow-failure anemias (a retrospective myelofibrosis series found ~44% favourable response) and historically as a palliative hormonal agent in advanced breast cancer (a 1975 case series), with no modern randomized trials and a mechanistic in-vitro anchor for its receptor binding. Against that sit the AAS harms it still carries: HPTA suppression, an adverse lipid shift (a German series documented hyperlipoproteinaemia and an MI on treatment) and virilization. Methenolone acetate is a 1-methyl steroid with a 17β-acetate ester; it is not 17α-alkylated. Anabolic steroids as a class have been associated with serious liver injury, peliosis and liver tumours. This class evidence does not quantify the risk of each methenolone form or establish that an injectable form is safe for the liver. It is a DEA Schedule III controlled substance and a prescription drug, NOT a dietary supplement or a longevity drug; non-medical use is unsupervised. Hence a low-ish score: real historical clinical use, but thin/old evidence and class harms.
1 trial ongoing or recruiting · none completed on ClinicalTrials.gov
Registered trials show research momentum for Methenolone (Primobolan), not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Nov 2026
Methenolone (brand name Primobolan) is a synthetic anabolic-androgenic steroid (AAS) — a 1-methylated derivative of dihydrotestosterone (DHT).
Because it is already 5α-reduced (a DHT analog), it is NON-AROMATIZABLE: it cannot be converted to estradiol, so it does not cause the estrogenic effects (gynecomastia, water retention) of testosterone.
It exists in two forms with very different pharmacology: an injectable enanthate ester (Primobolan Depot, given intramuscularly, long-acting) and an oral acetate tablet. Methenolone acetate is a 1-methyl steroid with a 17β-acetate ester; it is not 17α-alkylated.
Anabolic steroids as a class have been associated with serious liver injury, peliosis and liver tumours. This class evidence does not quantify the risk of each methenolone form or establish that an injectable form is safe for the liver.
Methenolone is regarded as a comparatively MILD steroid: in receptor-binding work it binds the androgen receptor in skeletal muscle and prostate more weakly than the strongest anabolics, making it weakly anabolic and weakly androgenic.
In the US it is a prescription drug and a Schedule III controlled substance under the Controlled Substances Act. Unusually for the compounds in this collection, methenolone's real clinical evidence is OLD and THIN rather than absent.
Its historical medical rationale was hematologic: like other anabolic steroids, it stimulates erythropoiesis and was used for decades to raise hemoglobin in bone-marrow-failure anemias — myelofibrosis with myeloid metaplasia, aplastic anemia, and the anemia of myelodysplastic syndrome.
The evidence here is retrospective and observational: a retrospective analysis of 39 myelofibrosis patients treated with anabolic steroids (including methenolone) in Japan (Shimoda 2007) found favourable hemoglobin responses in 44%, with adverse events described as moderate and transient, and a 2024 case report (Ushimaru) documents methenolone acetate plus darbepoetin used for the anemia of MDS.
It also had a second historical indication in oncology: as a palliative hormonal agent in advanced breast cancer, where a 1975 case series of 43 women treated with methenolone enanthate (Notter) reported objective remissions in 8 of 41 evaluable patients, with efficacy comparable to testosterone propionate but less virilization.
None of this is modern randomized evidence — it is the foundational, decades-old literature that defines the top of this compound's (modest) pyramid. The honest counterweight is the AAS safety profile, which methenolone shares despite its mildness.
As an androgen, methenolone in either form suppresses the hypothalamic-pituitary-testicular axis (LH, FSH, endogenous testosterone), shifts the lipid profile unfavourably (lower HDL, higher LDL — a 1981 German series during methenolone treatment of breast-cancer patients documented hyperlipoproteinaemia and a myocardial infarction in one patient), and can virilize (deepened voice, hirsutism) in women, sometimes irreversibly.
It is a WADA-prohibited doping agent.
The score reflects a real but OLD and THIN clinical evidence base — retrospective anemia series and historical breast-cancer case series, no modern RCTs — set against the fact that this is a controlled-substance prescription steroid, not a supplement or a longevity drug, whose non-medical bodybuilding use is unsupervised and carries the lipid, endocrine, liver and virilizing harms of its class.
This is a hormonal compound for harm-reduction information, not a recommendation.
Methenolone is a 1-methyl DHT derivative that binds and activates the androgen receptor in skeletal muscle and other tissues — but more weakly than the strongest anabolics, making it a comparatively mild androgen. Being already 5α-reduced, it is non-aromatizable: it cannot convert to estradiol, so it lacks the estrogenic effects of testosterone.
Like anabolic steroids generally, methenolone stimulates red-cell production — the mechanistic basis for its decades-old use to raise hemoglobin and reduce transfusion dependence in bone-marrow-failure anemias (myelofibrosis, aplastic anemia, myelodysplastic syndrome).
As an androgen, methenolone suppresses the hypothalamic-pituitary-testicular axis (LH, FSH, endogenous testosterone), lowers HDL and raises LDL cholesterol, and can virilize. Methenolone acetate is a 1-methyl steroid with a 17β-acetate ester; it is not 17α-alkylated. Anabolic steroids as a class have been associated with serious liver injury, peliosis and liver tumours. This class evidence does not quantify the risk of each methenolone form or establish that an injectable form is safe for the liver.
How Methenolone (Primobolan) works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Avoid — a controlled-substance prescription steroid, not a supplement; HPTA suppression, adverse lipids, virilization and the liver risks of anabolic steroids as a class, and not for self-experimentation.
High caution even when prescribed — although described historically as less virilizing than testosterone propionate, virilizing effects (voice deepening, hirsutism) can be permanent; discontinue at the first androgenic sign.
Major interaction — requires clinician-managed anticoagulant dose reduction and frequent INR checks.
Avoid entirely — androgenic; causes fetal virilization.
Anabolic-androgenic steroids potentiate warfarin, raising INR and bleeding risk; anticoagulant doses often need reduction with close INR monitoring under a clinician.
Potential liver risk warrants review before combining anabolic steroids with alcohol or other potentially hepatotoxic substances. The magnitude of the combined risk and any difference between methenolone formulations are not established here.
Anabolic steroids can improve insulin sensitivity and lower glucose, potentially requiring antidiabetic-dose adjustment.
Combining anabolic steroids can increase endocrine, lipid and other health risks. Oral 17α-alkylated steroids may add liver risk, but methenolone acetate itself is not 17α-alkylated. The magnitude and interaction pattern of these combinations are not established.
Tip: Lowered HDL and raised LDL cholesterol work against cardiovascular health; an older series documented hyperlipoproteinaemia and one myocardial infarction on treatment. Reversibility depends on discontinuation; monitor lipids.
Tip: Suppresses LH, FSH and endogenous testosterone like any exogenous androgen; clinician monitoring required. Suppression is generally reversible after discontinuation but recovery is not guaranteed.
Tip: Deepened voice, hirsutism, menstrual disruption and clitoral enlargement can occur and may be irreversible, even though methenolone is comparatively mild and historically described as less virilizing than testosterone propionate. Stop at the first sign of voice change in women.
Tip: Methenolone acetate is a 1-methyl steroid with a 17β-acetate ester; it is not 17α-alkylated. Anabolic steroids as a class have been associated with serious liver injury, peliosis and liver tumours. This class evidence does not quantify the risk of each methenolone form or establish that an injectable form is safe for the liver. Seek medical assessment today for jaundice, dark urine or right-upper abdominal pain; confusion, collapse or severe illness needs emergency help.
Methenolone (Primobolan) has an evidence score of 3.8/10 — emerging evidence based on 7 indexed studies. A mild anabolic-androgenic steroid (AAS) — brand Primobolan — sold as an injectable enanthate ester (Primobolan Depot) and an oral acetate tablet, and a DEA Schedule III CONTROLLED SUBSTANCE. It is a derivative of dihydrotestosterone (DHT), so it is non-aromatizable (cannot convert to estradiol) and only weakly androgenic and weakly anabolic relative to testosterone. Its real clinical history is OLD and THIN: it was used decades ago to raise hemoglobin in bone-marrow-failure anemias (myelofibrosis, aplastic anemia, MDS) and, historically, as a palliative hormonal agent in advanced breast cancer — evidence that is mostly retrospective series and case reports, not modern RCTs. Off-label it is used in bodybuilding for lean-mass retention while dieting. The honest counterweight: it is NOT a dietary supplement and NOT a longevity drug; non-medical use is unsupervised; and as an AAS it still suppresses the hypothalamic-pituitary-testicular axis, shifts lipids unfavourably, and can virilize. Methenolone acetate is a 1-methyl steroid with a 17β-acetate ester; it is not 17α-alkylated. Anabolic steroids as a class have been associated with serious liver injury, peliosis and liver tumours. This class evidence does not quantify the risk of each methenolone form or establish that an injectable form is safe for the liver. Described for harm-reduction information only — not a recommendation. Representative study: PMID 17483079.
Dosing for Methenolone (Primobolan): No self-directed dose is recommended here. Methenolone is listed in US DEA Schedule III (record dated 27 August 2026). That scheduling record does not establish current product authorisation or a dosing recommendation.
Timing is flexible for Methenolone (Primobolan) — consistent daily use matters more than the time of day. Timing and route depend on the actual prescribed preparation.
No consumer dose of Methenolone (Primobolan) is endorsed, so there is no dose at which it can be called safe. Talk to a healthcare provider before taking it. Reported side effects include liver injury, adverse lipid shift (low HDL, higher LDL), HPTA suppression. How often they occur is not established for all of them. Use caution if any of these apply to you: Anyone seeking it for body composition or athletic performance without a prescription — a DEA Schedule III controlled substance; it is not a dietary supplement, and laws on supply, possession, import and use depend on the country and circumstances; Pre-existing liver disease or abnormal liver tests require specialist assessment. Do not self-use methenolone.; Known or suspected prostate or male breast carcinoma; hypercalcemia.
What side effects does Methenolone (Primobolan) have?Don't take this if…
Epicatechin
Mixed evidenceDark chocolate flavanol with consistent human evidence for improved endothelial function and modest blood pressure reduction. Muscle-building claims are not supported in humans.
Oxandrolone (Anavar)
Too few graded studiesA prescription oral anabolic-androgenic steroid (AAS) — brand Anavar/Oxandrin — and a DEA Schedule III CONTROLLED SUBSTANCE. It has genuine randomized-trial evidence in formerly FDA-approved (withdrawn June 2023), supervised muscle-wasting settings: it adds lean body mass, speeds wound healing and shortens hospital stay in severe burns, raises body weight in HIV-associated wasting, and modestly increases adult height in Turner syndrome. But it is 17α-alkylated and hepatotoxic (dose-related transaminase rises, cholestasis, and — with anabolic steroids generally — peliosis and liver tumours), it sharply lowers HDL and raises LDL cholesterol, and it suppresses the hypothalamic-pituitary-testicular axis and virilizes. It is NOT a dietary supplement and NOT a longevity drug; non-medical bodybuilding use is unsupervised and carries real liver, lipid, and endocrine harm. Described for harm-reduction information only — not a recommendation.
Nandrolone (Deca-Durabolin)
Too few graded studiesAn injectable anabolic-androgenic steroid (AAS) — brand Deca-Durabolin, the long-acting decanoate ester of 19-nortestosterone — and a DEA Schedule III CONTROLLED SUBSTANCE. It has genuine randomized-trial evidence in supervised, catabolic-illness settings: it adds lean body mass and weight in HIV-associated wasting, adds muscle mass and physical function in dialysis patients, and raises hemoglobin in dialysis anemia (a historic FDA-approved indication, since largely replaced by erythropoietin). But it suppresses the hypothalamic-pituitary-gonadal axis — and because it is a long-ester 19-nortestosterone with progestogenic activity, that suppression and the resulting sexual dysfunction ('deca dick') can be prolonged. It worsens the lipid profile (lowers HDL), is associated with cardiac remodelling/cardiomyopathy and premature atherosclerosis in long-term high-dose users, and virilizes. It is NOT a dietary supplement and NOT a longevity drug; non-medical bodybuilding/performance use is unsupervised and carries real cardiovascular, endocrine and sexual harm. Described for harm-reduction information only — not a recommendation.
Oxymetholone (Anadrol)
Too few graded studiesA potent prescription ORAL anabolic-androgenic steroid (AAS) — brand Anadrol/Anapolon — and a DEA Schedule III CONTROLLED SUBSTANCE. Oxymetholone has a US FDA approval record for ANADROL-50 under NDA 016848. The 2026 Orange Book lists this product as discontinued. This record does not establish current availability or authorisation of another product or use. It has real randomized-trial evidence in supervised muscle-wasting settings: it adds body weight and lean/body cell mass in HIV-associated wasting, raises lean mass and strength in older men, and increases haemoglobin and muscle mass in dialysis patients; a Cochrane review found limited evidence, from one 24-person study, that it raises haemoglobin in the anaemia of chronic kidney disease, and judged the evidence insufficient. But it is 17α-alkylated and markedly HEPATOTOXIC — anabolic steroids as a class have been associated with cholestasis, peliosis hepatis with life-threatening liver failure or bleeding into the abdomen, and liver tumours, including reported fatal malignancies (historical Anadrol-50 US boxed warning, 2004). It also sharply lowers HDL and raises LDL cholesterol, suppresses the hypothalamic-pituitary-testicular axis, and virilizes. It is NOT a dietary supplement and NOT a longevity drug; non-medical bodybuilding use is unsupervised and carries those liver, lipid, and endocrine harms unmonitored. Described for harm-reduction information only — not a recommendation.
Explore: Best supplements for Athletic Performance
Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 7 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Tap node to isolate • Pinch to zoom • Tap edge for research