What is testosterone cypionate?

Testosterone cypionate is an esterified form of testosterone delivered via intramuscular injection. The cypionate ester lengthens the hormone's half-life in the body, allowing injections to be spaced 7 to 14 days apart rather than requiring daily administration. This extended interval makes it practical for clinical use and patient compliance.

It remains the most prescribed testosterone formulation in the United States for testosterone replacement therapy providers. The popularity stems from its long track record, stable pharmacokinetics, lower cost compared to newer formulations, and the established protocols clinicians follow for dosing and monitoring. Standard therapeutic doses typically range from 50 mg to 100 mg per week, though individual protocols vary based on baseline hormone levels and clinical goals.

Testosterone cypionate comes as an oil-based suspension in vials and is administered with a small gauge needle into the gluteal muscle, quadriceps, or deltoid. Because it is a controlled substance, it is available only through prescription and requires baseline testing and regular follow-up labs to monitor therapeutic levels and manage potential side effects. Its widespread use in clinical practice, combined with decades of safety data, has made it the reference standard against which newer formulations are often compared.