cat. no. TESTOSTERONE-CYPIONATE
Testosterone cypionate
Androgen (esterified testosterone, injectable depot)
also: Depo-Testosterone / Test C / Test Cyp
Reviewed 2026-08-29 · 4 sources
At a glance
What it is
Testosterone cypionate is testosterone with a fatty-acid ester (cypionate) attached, dissolved in oil and injected into muscle or under the skin. The oil forms a small depot that releases the hormone slowly as the body clips off the ester, so one shot keeps working for weeks instead of the minutes plain testosterone would last. Its half-life injected intramuscularly is about 8 days, which is why the FDA label doses it every 2 to 4 weeks for hypogonadism. Levels are not flat: after an injection testosterone and estradiol peak within a few days and then drift down, which is the trade-off behind the more frequent split-dose schedules people use.
Dose ranges
Study-backed ranges carry a source you can open. Community ranges are widely reported but not clinically established - treat them as what people do, not as advice.
Male hypogonadism replacement (Depo-Testosterone FDA label)
study50-400 mg
intramuscular, once every 2 to 4 weeks
Community-reported weekly TRT protocol (split dosing to smooth peaks and troughs) - community-reported, not clinically established
community100-200 total per week, commonly split into 2 injections of 50-100 mg
intramuscular or subcutaneous, once or twice weekly
Subcutaneous weekly dosing studied in men on testosterone therapy (Kohn et al, 2017)
study50-100 (median 75) mg
subcutaneous, once weekly
Storage
Reconstituted
Store at 20 to 25 C (68 to 77 F), USP Controlled Room Temperature, per the Depo-Testosterone label. The product is a pre-made sterile oil solution, not a powder for reconstitution. Warming the vial and rolling (not shaking) helps if the oil has thickened when cold.
Tools for Testosterone cypionate
Common stacks
Interactions & cautions
The Depo-Testosterone label directs checking hemoglobin and hematocrit periodically during long-term androgen use to detect polycythemia, since testosterone can raise red-cell mass. Injected testosterone cypionate is aromatized to estradiol: in 11 hypogonadal men, 200 mg intramuscular produced a threefold rise in serum testosterone (peak days 2 to 5) alongside a threefold rise in estradiol (days 2 to 7) (Nankin, 1987). It also suppresses the hypothalamic-pituitary-testicular axis - luteinizing hormone falls and, in a population PK/PD study, higher doses caused more severe and prolonged suppression of endogenous testosterone, LH, and spermatogenesis, which is the basis for the fertility concern on testosterone therapy (Rasmussen et al, 2018). The label notes androgens may increase sensitivity to oral anticoagulants, so warfarin dosing may need reduction. Edema, with or without congestive heart failure, may be a serious complication in patients with pre-existing cardiac, renal, or hepatic disease. It is contraindicated in men with known or suspected carcinoma of the prostate gland or the breast, and in patients with serious cardiac, hepatic, or renal disease (label).
Questions people ask
What is the half-life of testosterone cypionate?
About 8 days when injected intramuscularly, per the Depo-Testosterone FDA label. That slow release is what lets it be dosed every 2 to 4 weeks rather than daily.
What is the FDA-labeled dose for low testosterone?
The Depo-Testosterone label states 50 to 400 mg intramuscularly every 2 to 4 weeks for replacement in the hypogonadal male. This is a reported label range, not personal medical advice - testosterone is a Schedule III controlled substance and dosing is a prescriber's decision.
Why do people split it into weekly or twice-weekly injections?
Because levels swing. A single 200 mg intramuscular dose spiked testosterone and estradiol about threefold within days 2 to 7 and then fell back toward baseline by roughly two weeks (Nankin, 1987). Smaller, more frequent injections are a community practice aimed at flattening those peaks and troughs; it is not the FDA-labeled schedule.
Does testosterone cypionate affect fertility?
It can suppress it. Injected testosterone lowers luteinizing hormone and, at higher doses, causes more severe and prolonged suppression of the body's own testosterone and of sperm production (Rasmussen et al, 2018). This is why hCG or other adjuncts are sometimes used alongside it - discuss any fertility plan with a clinician.
How is it stored?
At room temperature, 20 to 25 C (68 to 77 F), per the label. It ships as a ready-to-use sterile oil, not a powder you reconstitute; if the oil is cold and thick, warming and gently rolling the vial helps.
Sources
- [1]DEPO-TESTOSTERONE (testosterone cypionate injection) - FDA Prescribing Information (DailyMed)labelAvailable strengths 100 and 200 mg/mL; hypogonadism dose 50-400 mg intramuscular every 2 to 4 weeks; intramuscular half-life approximately 8 days; storage at 20-25 C; periodic hematocrit monitoring for polycythemia; increased sensitivity to oral anticoagulants; edema warning; prostate and breast carcinoma and serious cardiac/hepatic/renal disease contraindications.
- [2]Nankin HR. Hormone kinetics after intramuscular testosterone cypionate (Fertil Steril, 1987) PMID 3595893studyIn 11 hypogonadal men, 200 mg intramuscular testosterone cypionate produced a threefold rise in serum testosterone (peak days 2 to 5), a 4.5-fold rise in absolute free testosterone, and a threefold rise in estradiol (days 2 to 7), with levels declining to baseline by about days 13 to 14 and luteinizing hormone suppressed - documenting both aromatization to estradiol and the peak-to-trough swing.
- [3]Kohn TP et al. Serum Testosterone Concentrations Remain Stable Between Injections in Patients Receiving Subcutaneous Testosterone (PMC5686655)studyWeekly subcutaneous testosterone cypionate at 50-100 mg (median 75 mg) kept total and free testosterone stable and within the normal range between injections - the evidence behind weekly subcutaneous dosing.
- [4]Rasmussen JJ et al. Population Pharmacokinetic/Pharmacodynamic Modeling of Depot Testosterone Cypionate in Healthy Male Subjects (CPT Pharmacometrics Syst Pharmacol, 2018) PMID 29436172studyA linear one-compartment model described the depot testosterone cypionate concentration-time profile; higher doses (250-500 mg/week) caused more severe and prolonged suppression of endogenous testosterone, luteinizing hormone, and spermatogenesis - the basis for the HPTA and fertility suppression note.
What we could not verify
The Depo-Testosterone DailyMed label does not print an explicit 'aromatizes to estradiol' sentence; the aromatization and estradiol-rise claim rests on the primary PK study (Nankin 1987, PubMed 3595893), which was read through NCBI eutils because the PubMed HTML page returned a cookie-consent wall. fda.gov and accessdata.fda.gov were not used (blocked). The population PK abstract (PubMed 29436172) reports the one-compartment model, clearance, and volume of distribution but does not state a numeric half-life, so the ~8-day half-life is anchored to the DailyMed label rather than that paper. The community weekly/split TRT range (100-200 mg per week split into 2 injections) is self-reported practice, not an FDA-labeled schedule and not clinical guidance; the label frequency is every 2 to 4 weeks. All dose figures here are reported facts with a source, not a recommended personal dose - testosterone cypionate is a US Schedule III controlled substance.