Important: this page is educational. Testosterone cypionate is a controlled prescription drug and requires a clinician evaluation and ongoing lab monitoring.
What is testosterone cypionate?
Testosterone cypionate is a long-acting injectable form of testosterone, the primary male androgen. The cypionate ester slows release from the injection site so blood levels rise and fall gradually over roughly a week. It is the workhorse of testosterone replacement therapy in the United States.
How does testosterone cypionate work?
Once injected, the ester is cleaved and free testosterone enters circulation. Testosterone binds the androgen receptor across muscle, bone, brain, and reproductive tissue. It also converts to estradiol through aromatase and to DHT through 5-alpha reductase. Both metabolites contribute to its full effect on libido, mood, body composition, and bone health.
How is testosterone cypionate dosed?
Typical replacement doses range from 50 to 200 mg per week. The most common starting point is 100 mg weekly, adjusted by trough total testosterone, free testosterone, hematocrit, and symptoms.
Dosing frequency matters as much as total dose. Weekly injections produce a peak roughly 48 to 72 hours after the shot and a trough at day seven. Twice-weekly dosing flattens that curve. Daily microdosing produces near-flat serum levels and tends to reduce estradiol swings, which some men find easier to tolerate. Subcutaneous injection works as well as intramuscular for most men and is less painful.
Cypionate vs enanthate vs undecanoate
Cypionate and enanthate are nearly interchangeable; enanthate has a slightly shorter half-life. Testosterone undecanoate (Aveed injectable, Jatenzo oral) has a much longer half-life dosed every ten weeks intramuscularly or twice daily orally. Choice usually comes down to availability, cost, and dosing preference.
How long until testosterone cypionate works?
Libido and energy often shift in the first two to four weeks. Mood and cognition follow within six to eight weeks. Body composition changes (more lean mass, less fat) appear over three to six months and continue for a year or more.
Side effects of testosterone cypionate
The most common monitorable issues are erythrocytosis (rising hematocrit), estradiol-related symptoms (water retention, gynecomastia in some men), acne and oily skin, and worsening sleep apnea. Long-term cardiovascular safety data has improved with the TRAVERSE trial, though monitoring still matters.
The biggest cost most men do not anticipate is fertility suppression: exogenous testosterone shuts down LH and FSH, which shrinks the testes and stops sperm production. Read more in our TRT fertility cost breakdown.
Who should not take testosterone cypionate?
Contraindicated in active prostate or breast cancer, untreated severe sleep apnea, uncontrolled heart failure, elevated hematocrit at baseline, and active fertility plans without sperm banking or concurrent HCG. Use caution in men with a history of thrombosis or stroke.
Cypionate vs enclomiphene
Enclomiphene raises endogenous testosterone by blocking estrogen feedback at the hypothalamus. It preserves fertility but produces a smaller and less predictable testosterone response than direct injection. For most men who want full restoration, cypionate is more reliable. For men with mild deficits and active fertility goals, enclomiphene is often the right first step.