Masteron

evidence score

anabolic

Scheduled Substance

4 studies

Drostanolone PropionateDrostanolone EnanthateDrostanolone+1 more

Masteron (Drostanolone) is a DHT-derived anabolic steroid originally developed and approved for inoperable breast cancer treatment in the 1970s. Available as propionate (short-acting, EOD injections) and enanthate (long-acting, twice-weekly). Unique among anabolics for its anti-estrogenic properties — drostanolone acts as an aromatase inhibitor and directly competes with estrogen at the receptor level. Does not aromatize. Produces hard, dense muscle appearance with minimal water retention, making it popular pre-competition. Low anabolic potency relative to other steroids. Suppresses testosterone. Schedule III controlled substance.

Evidence

Emerging evidence

Safety

Unknown safety profile

Clinical Status

Approved

Research Sync

Feb 19, 2026

Dosing

Typical

400 mg

200 mgRange600 mg

FrequencyPropionate: EOD IM injection. Enanthate: twice weekly IM.

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Pharmacology

Half-life~2–3 days (propionate); ~10 days (enanthate)

Onset2–3 weeks

DurationCycle length 8–12 weeks; suppression recovery 4–8 weeks

Routes

intramuscular

Evidence Score

Level C — Weak

4 studies indexed

Scoring Factors

Volume(40%)~14/100

Quality(30%)~40/100

Sample Size(10%)~79/100

Consistency(10%)~79/100

Replication(5%)~79/100

Recency(5%)~79/100

Scores estimated from study counts. Exact breakdown computed after research sync.

Evidence Levels

AScore ≥75 with at least 1 meta-analysis and 3+ RCTs

BScore ≥50 with at least 1 RCT or meta-analysis

CScore ≥25 — observational or animal evidence only

DScore <25 — very limited or preclinical data

Plain-English Snapshot

Masteron is currently categorized as a anabolic compound.

Evidence is early (41/100): there are positive signals, but the 4-study base is still thin.

Safety scoring is incomplete. Start conservatively and monitor carefully.

Core mechanism

DHT-derived androgen with intrinsic anti-estrogenic activity; no aromatization; competes with estrogen at receptor level; moderate AR agonist with hardening/drying cosmetic effects

Practical Context

Strongest current signals

Level D: The duration of prior ET+CDK4/6i ≥12 months in metastatic breast cancer was associated with a clinically meaningful improvement in PFS for elacestrant compared with SOC and was consistent across all subgroups evaluated in patients with ER+, HER2−, ESR1-mutated tumors.
Level D: The present review deliberates the pathophysiology and the role of aromatase in estrogen biosynthesis and various AIs from multiple origins, such as synthetic and semi-synthetic, have been discussed.
Level D: The Phase III, randomized, double-blind, PBO-controlled CAPItello-291 trial investigated the efficacy and safety of capivasertib + fulvestrant in patients with AI-resistant HR+/HER2– ABC and found that the most frequently reported grade ≥3 AEs were rash.