Masteron Propionate (drostanolone propionate) offers several key benefits and pros in bodybuilding, particularly in cutting and pre-competition phases for rapid physique refinement
$145
Mast P 100 is drostanolone propionate at 100 mg/mL in a 10 mL vial. Drostanolone is a derivative of DHT, and the propionate ester is the short one, which makes this the fast-acting version of Masteron.
It has a genuine medical history that explains what it does. Drostanolone propionate was first described in 1959 and introduced for medical use in the United States in 1961, and it was prescribed to treat breast cancer in women — specifically because of its antiestrogenic activity. It is no longer marketed pharmaceutically. That origin is the key to understanding the compound: Masteron is, at heart, an antiestrogenic androgen.
Drostanolone binds the androgen receptor with a reported androgenic-to-anabolic ratio of roughly 1:3 to 1:4. On paper that makes it a modest anabolic. In practice nobody runs Masteron to grow — they run it for what it does to estrogen and to how a physique looks.
Two properties define it:
It is also not 17α-alkylated, so unlike the methylated orals such as Winstrol it is not known to cause hepatotoxicity.
Drostanolone propionate has a reported elimination half-life of approximately 2 days by intramuscular injection. The clinical regimen for breast cancer was 100 mg one to three times weekly, with 200 mg twice weekly also used.
A two-day half-life means blood levels fall away quickly. Masteron propionate is injected frequently — commonly every other day — to hold levels steady. If you want the same compound with fewer injections, Mast E 200 uses the long enanthate ester instead.
Masteron is sold everywhere on photographs of extremely lean people and words like “shredded” and “stage-ready.” Here is the honest version.
Masteron does not burn fat. It is not a fat-loss drug and it has no meaningful thermogenic action. The dry, hard, striated look people associate with it is the look of low body fat — Masteron only makes visible what is already there. Run it at 18% body fat and you will see essentially nothing for your money, and you will conclude the vial was fake when the vial was fine.
This is why Masteron has a reputation as a contest-prep compound rather than an off-season one. It is a finishing tool. If you are not already lean, your money is better spent almost anywhere else, and we would rather tell you that than sell you a vial you will be disappointed by.
Same hormone, different ester:
Neither is stronger. Propionate is chosen for control, enanthate for convenience.
Masteron is a DHT derivative, and the androgenic side effects that come with that are real: accelerated hair loss in people genetically predisposed to it, and androgenic pressure on the prostate. If male pattern baldness runs in your family, Masteron is one of the more likely compounds to bring it forward.
Here is the nuance almost nobody mentions. Many people reach for finasteride to blunt androgenic side effects. Finasteride works by inhibiting 5α-reductase, the enzyme that converts testosterone into DHT. Drostanolone is not a substrate for 5α-reductase — it is already a DHT derivative. There is no conversion step for finasteride to block, so it has nothing to act on. Finasteride will not protect your hair from Masteron the way it might from testosterone.
That is worth knowing before you start rather than after.
Masteron suppresses your own testosterone production, and at a 1:3-1:4 ratio it is not a compound to run as your only androgen. It is almost always run alongside a testosterone base — Test P 100 matches its short ester and injection schedule, or Test E 250 if you prefer a longer one.
Because Masteron is antiestrogenic, some people find they need less Arimidex or Aromasin than they would on the same testosterone dose without it. That is a reason to re-check rather than to assume — stacking a full aromatase inhibitor dose on top of an antiestrogenic compound is a good way to drive estradiol too low, which brings its own joint, mood and libido problems. Proviron is the closest oral analogue if you want a similar effect in tablet form.
Masteron is not liver-toxic and does not aromatise, which makes it one of the easier compounds on paper. It is still suppressive, and DHT derivatives are not kind to blood lipids — HDL in particular. Blood pressure and a lipid panel are worth watching. Because the propionate ester clears in days rather than weeks, PCT with Nolvadex and Clomid can begin sooner after the last injection than with a long-ester compound.
Every batch goes for independent HPLC analysis and we publish the reports rather than describing them. The Mast P batch submitted in 2026 was assayed by Janoshik at 97.50 mg/mL against its 100 mg/mL label — read the full report (#136661) yourself. Every report we hold is on our HPLC test reports page.
We publish the real number rather than a round one. A vendor who will not show you a report is asking you to take their word for what is in the vial.
Masteron for sale from KGEAR U.S ships domestically within the United States. If you are looking to buy Mast P 100 online — drostanolone propionate, 100 mg/mL, 10 mL — this vial is third-party tested with the report linked above. Checkout is crypto; our how to buy Bitcoin guide covers it if that is new. Browse the rest of the injectables range, or the compounds Masteron is usually run with: Test P 100, Tren A 100 and Anavar 25mg.
What is the half-life of Masteron propionate?
Approximately 2 days by intramuscular injection. That short half-life is why Mast P is typically injected every other day rather than weekly.
Does Masteron aromatise?
No. As a DHT derivative it is not a substrate for aromatase, so it cannot convert to estrogen. It also has antiestrogenic properties of its own — it was originally used to treat estrogen-driven breast cancer.
Does Masteron burn fat?
No. This is the most common misunderstanding about it. Masteron has no meaningful fat-loss action. The hard, dry look attributed to it is the look of low body fat, which Masteron reveals rather than creates.
Will I see anything from Masteron at 15-18% body fat?
Realistically, no. Masteron is a finishing compound. If the fat covering the muscle has not already come off, there is nothing for it to bring out.
Mast P or Mast E — which is better?
Neither. Same hormone. Propionate has a ~2 day half-life and needs every-other-day injections but clears fast; enanthate needs fewer injections but lingers. Pick on schedule, not on strength.
Will finasteride stop Masteron causing hair loss?
No. Finasteride blocks 5α-reductase, and drostanolone is not a substrate for that enzyme — it is already a DHT derivative, so there is no conversion for finasteride to prevent.
Is Masteron liver toxic?
It is not 17α-alkylated and is not known to cause hepatotoxicity, unlike the methylated orals. It is still suppressive and is not kind to HDL cholesterol.
Is this Masteron lab tested?
Yes, independently by Janoshik. The batch assayed at 97.50 mg/mL against a 100 mg/mL label, and the report is linked on this page.
Disclaimer: this information is provided for educational purposes and does not constitute medical advice. Drostanolone propionate is not approved for human use without a prescription from a licensed healthcare professional. Consult a qualified medical practitioner before beginning any hormone protocol.
This product is intended for research or educational purposes only and is not approved for human use unless prescribed by a licensed healthcare professional. Always consult a medical expert before beginning any supplement or hormone program.
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