Is Testosterone cypionate legal in the United Kingdom?

The most prescribed injectable testosterone in the United States. Its eight-day half-life is why a single weekly shot produces a peak and a crash, and why splitting the same total flattens the curve.

This is the vial most people are handed. It is testosterone with an eight-carbon cypionate ester attached, dissolved in oil, which slows release from the injection site and turns a hormone that would clear in hours into one dosed weekly.

Mechanism: Testosterone esterified at the 17-beta hydroxyl with cyclopentylpropionic acid, which makes it lipophilic enough to remain in an oil depot at the injection site. Tissue esterases cleave the ester gradually to release free testosterone, so the ester chain length governs the release rate rather than the activity.

Regulatory history: FDA-approved as Depo-Testosterone for male hypogonadism. Schedule III controlled substance. Not approved for women or for age-related low testosterone in men with normal levels.

Licenses medicines for the UK market. A compound without a marketing authorisation is an unlicensed medicine, which can only lawfully be supplied for human use through a prescriber under the specials scheme, not sold as a research product.

The classification above is the The Longevity Archive reading of Medicines and Healthcare products Regulatory Agency listings for Testosterone cypionate at the reviewed date, not a legal opinion. Rules change, and importing, prescribing and possessing a compound can each be treated differently. Check the regulator directly before acting on anything here.