Testosterone Cypionate
Also known as: Test Cyp, Depo-Testosterone
A long-acting injectable testosterone ester used clinically for testosterone replacement therapy (TRT) in men with diagnosed hypogonadism. Prescription medication.
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Mechanism of Action
Testosterone cypionate is an esterified form of the endogenous androgen testosterone. After intramuscular or subcutaneous injection it is slowly released and cleaved to free testosterone, which binds the androgen receptor to drive secondary sexual characteristics, muscle protein synthesis, bone density, erythropoiesis, libido, and mood. The cypionate ester extends the half-life so dosing every 3.5-7 days maintains stable serum levels.
- Half-life
- ~8 days (cypionate ester)
- Administration Routes
- Intramuscular, Subcutaneous
- Research Status
- Clinical
Reported Benefits
- Restores serum testosterone in diagnosed hypogonadism
- Supports libido, energy, mood, and cognition when levels are low
- Preserves lean mass and bone mineral density
Potential Side Effects
- Erythrocytosis (elevated hematocrit)
- Estrogen-related effects (water retention, gynecomastia) via aromatization
- Testicular atrophy and suppressed fertility
- Acne, oily skin
Common Dosing
TRT protocols reported in the literature are typically 100-200 mg per week, often split into two injections, titrated to trough serum testosterone and symptoms. Dosing must be individualized and supervised by a physician.
The dosing information above is aggregated from research literature and anecdotal community reports for educational purposes only. It is not a recommendation, prescription, or medical advice. Peptides are sold as research chemicals only and are not intended for human use.
Contraindications
- Prostate or breast cancer
- Untreated erythrocytosis
- Pregnancy (contraindicated) and men seeking fertility without adjuncts
- Uncontrolled cardiovascular disease — use only under medical supervision
HCG (Human Chorionic Gonadotropin)
A glycoprotein hormone produced in pregnancy that mimics luteinizing hormone, used clinically to stimulate gonadal function. It is studied to support testosterone production and fertility.
Anastrozole
An aromatase inhibitor used off-label to control estrogen elevation on testosterone therapy. Prescription medication (approved for breast cancer).
Enclomiphene
A selective estrogen receptor modulator (SERM) that raises the body's own testosterone by increasing LH and FSH. Investigational; used off-label.
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Population Pharmacokinetic/Pharmacodynamic Modeling of Depot Testosterone Cypionate in Healthy Male Subjects
2018
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Comparison of Outcomes for Hypogonadal Men Treated with Intramuscular Testosterone Cypionate versus Subcutaneous Testosterone Enanthate
2022
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Comparison of Hematocrit Change in Testosterone-deficient Men Treated With Intranasal Testosterone Gel vs Intramuscular Testosterone Cypionate: A Randomized Clinical Trial
2023
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Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline
2018