Testosterone Cypionate
A long-acting testosterone ester near-identical in practice to enanthate, differing only in a marginally longer half-life. The most common TRT ester in the United States.
01 Overview
Cypionate is an eight-carbon ester of testosterone. Once cleaved it is simply testosterone, so its entire effect and side-effect profile matches enanthate — the choice between them is regional habit, not pharmacology.
The slightly longer ester means marginally flatter serum levels, but the difference is small enough to be clinically irrelevant for most.
02 Mechanism
Identical to testosterone once the ester is cleaved: androgen-receptor agonism, with aromatisation to oestradiol and 5α-reduction to DHT accounting for most of the side-effect profile.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Therapeutic | 75–200 mg/wk | IM | Standard US TRT range, usually split twice weekly. |
| Common | 300–500 mg/wk | IM | Typical first non-medical protocol; interchangeable with enanthate. |
Ester comparison
| Ester | Half-life | Injection freq. | Testosterone by mass |
|---|
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Increased lean body massSame dose-response as other testosterone esters | +3–6 kg / 10 wk | Clinical | |
| Improved libido and moodReliable where baseline testosterone is low | Marked in hypogonadism | Clinical | |
| Increased bone mineral densityOver 12–36 months of therapy | +3–8% | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| ErythrocytosisRaised haematocrit, as with all testosterone. The most consistently abnormal lab value. | Severe | Common | Clinical | |
| HPTA suppressionTesticular atrophy and suppressed spermatogenesis. | Severe | Universal | Clinical |
06 Commonly used with
What testosterone is combined with, and why. This is about intent rather than safety — the interactions table below covers what is dangerous. Nothing here is listed without what it costs.
| Compound | Frequency | Purpose & trade-off |
|---|---|---|
| Stacked compounds | ||
| NandroloneDeca | Long-ester nandrolone matches cypionate's slow kinetics for steady mass and joint comfort on a shared injection schedule.Trade-off: Adds progestogenic and prolactin-driven side effects plus prolonged HPTA suppression that lengthens recovery. | |
| BoldenoneEQ | Boldenone contributes appetite, endurance and slow lean gains that complement a testosterone base without heavy estrogen load of its own.Trade-off: Very long half-life delays steady state and clearance, and its RBC-raising effect stacks with testosterone to push haematocrit high. | |
| Dianaboloral kickstart | An oral kickstart delivers rapid strength and size in the first weeks while injected cypionate builds to full blood levels.Trade-off: Adds hepatic strain, water retention and extra aromatisation on top of the testosterone during the overlap. | |
| Support & ancillaries | ||
| AnastrozoleAI | Controls estrogen from testosterone aromatisation to limit gynecomastia and water retention at higher doses.Trade-off: Over-suppression crashes estrogen, harming lipids, libido, mood and joint comfort. | |
| Post-cycle | ||
| TamoxifenPCT | Restarts endogenous testosterone by blocking estrogen feedback at the hypothalamus after the cypionate clears.Trade-off: Can cause mood changes and visual disturbances, and recovery is unreliable after long or heavily suppressive cycles. | |