Masteron vs MK-2866
Moderate Research vs Moderate Research
monitor Mechanism-based · 55% Both Masteron and MK-2866 suppress the HPTA axis. Combined suppression deepens shutdown and extends recovery time. Plan PCT accordingly and monitor LH/FSH/testosterone.
Molecular Data
Masteron MK-2866
Weight 304.47 Da (base) 389.33 Da
Half-life ~2 days (propionate), ~10 days (enanthate) ~24 hours
Type DHT-derived anabolic steroid (C20H32O2) Non-steroidal selective androgen receptor modulator (C19H14F3N3O3)
Key Benefits
Masteron
01 Produces a hard, dry, and grainy appearance by eliminating subcutaneous water retention
02 Mild anti-estrogenic properties that can reduce or replace the need for aromatase inhibitors on cycle
03 Does not aromatize, eliminating estrogen-mediated side effects from the compound itself
04 Enhances the visual effects of other steroids in a stack by reducing water retention and bloat
05 Modest increases in strength without significant weight gain, useful for weight-class athletes
06 Improves muscle density and vascularity at low body fat percentages
07 Well-tolerated with a relatively mild side effect profile compared to other anabolic steroids
08 Short detection window with propionate ester compared to many other injectable steroids
MK-2866
01 Increases lean body mass in a dose-dependent manner with clinical trial support
02 Preserves muscle mass during caloric deficit or catabolic conditions
03 Selective tissue activity reduces androgenic side effects compared to anabolic steroids
04 Oral bioavailability eliminates the need for injections
05 Does not aromatize to estrogen, avoiding gynecomastia and water retention
06 Improves physical function and stair-climbing power in clinical populations
07 Long 24-hour half-life allows convenient once-daily dosing
08 Mild side effect profile at commonly studied doses
Dosing Protocols
Masteron
300-500 mg/week / Every other day (propionate) or 2x per week (enanthate)
Cutting / Aesthetic Enhancement 300-400 mg/week Every other day (propionate) or 2x per week (enanthate)
Contest Preparation 400-500 mg/week Every other day or daily (propionate)
AI Replacement / Estrogen Management 200-300 mg/week Every other day (propionate) or 2x per week (enanthate)
MK-2866
10-25 mg/day oral / Once daily
Side Effects
Masteron
Hair loss and accelerated male pattern baldness (significant risk as a DHT derivative - the most commonly reported side effect)
Acne and increased skin oiliness, particularly on the back and shoulders
Suppression of natural testosterone production (requires PCT or ongoing TRT)
Injection site pain or discomfort (more common with propionate ester)
Mild aggression or irritability from elevated androgenic activity
HDL cholesterol suppression and adverse lipid profile changes
MK-2866
Mild testosterone suppression (dose-dependent, typically 10-30% reduction at 25 mg)
HDL cholesterol reduction (10-20% suppression observed in clinical trials)
Headaches, particularly during the first 1-2 weeks
Mild back pain or muscle cramps
Transient fatigue toward the end of longer cycles
Slight reduction in libido at higher doses or extended cycle lengths
Contraindications
Prostate cancer (active or history of hormone-sensitive prostate cancer)
Breast cancer in males
Pregnancy or potential for pregnancy (causes virilization of female fetus)
Known hypersensitivity to drostanolone or any formulation components
Severe hepatic impairment
Pre-existing significant hair loss where further androgenic exposure is unacceptable
Polycythemia (hematocrit above 54% at baseline)
Uncontrolled cardiovascular disease or severe dyslipidemia
Active liver disease or significantly elevated liver enzymes
Hormone-sensitive cancers (breast, prostate) without oncologist clearance
Pregnancy or breastfeeding (potential endocrine disruption to fetus/infant)
Individuals under 21 years of age (risk of premature HPTA disruption during development)
Concurrent use of hepatotoxic medications without liver function monitoring
Known hypersensitivity to MK-2866 or any formulation excipients
Competitive athletes subject to WADA or USADA anti-doping testing
Research Evidence
Masteron MK-2866
Status Moderate Research Moderate Research
References 5 studies 5 studies
Latest March 2020 —
FDA Approved No No
This comparison is for educational and research purposes only. Consult a healthcare professional before use.