Testosterone cypionate (often called “Test C”) has a half-life of approximately eight days, meaning half the injected dose is cleared from your body roughly every eight days. After a single injection, it takes about five to six half-lives for a drug to be effectively eliminated, which puts total clearance at around 40 to 48 days. However, the timeline that matters most depends on why you’re asking: whether you want to know when testosterone levels drop back to baseline, when you’ll feel the effects fade, or how long it’s detectable on a drug screening.
How Test C Moves Through Your Body
When testosterone cypionate is injected into muscle tissue, it sits in a small oil depot that releases slowly into your bloodstream. Testosterone levels rise into a supraphysiological range (above normal) within 24 to 48 hours after injection, then peak around day two or three. From there, levels gradually decline over the next two weeks, eventually dropping into the low or hypogonadal range by the end of a typical dosing interval. This slow-release pattern is why doctors prescribe injections every two to four weeks rather than daily.
The eight-day half-life is an average. Individual factors like your injection site, body fat percentage, metabolism, and the size of your dose all influence how quickly or slowly the testosterone clears. A larger dose creates a bigger depot of oil in the muscle, which can take slightly longer to fully absorb and break down.
When Levels Return to Baseline
If you’ve only had a single injection, your testosterone levels will typically fall back into the normal or low-normal range within about two weeks. By the end of week three, most of the exogenous testosterone from that shot is gone. Full pharmacological clearance, where trace amounts are no longer measurable in blood, takes roughly five to six weeks based on the eight-day half-life.
If you’ve been on testosterone cypionate for months or longer, the picture changes. With repeated injections every one to two weeks, the drug accumulates and reaches a steady state, usually around weeks three to four of consistent dosing. Once you stop, it takes longer for your body to fully clear the accumulated testosterone compared to stopping after a single shot. You can expect levels to taper over several weeks, with noticeable changes in energy, mood, and libido beginning within the first one to two weeks after your last injection and continuing to shift over the following month.
Detection Windows for Drug Testing
Standard clinical blood work measures total testosterone levels but doesn’t distinguish between testosterone your body makes naturally and testosterone from an injection. For that reason, athletic drug testing uses different methods, primarily looking for the testosterone-to-epitestosterone (T/E) ratio in urine or detecting the actual ester molecule in blood.
The World Anti-Doping Agency (WADA) has studied how long various testosterone esters remain detectable in blood. While WADA’s published research doesn’t isolate cypionate specifically, closely related esters provide useful reference points. Short-chain esters like testosterone propionate remain detectable for four to five days, while medium-chain esters like isocaproate show detection times of at least eight days. Longer-chain esters like testosterone undecanoate were still detectable 60 days after a single administration. Testosterone cypionate, a medium-to-long chain ester, likely falls somewhere in the range of two to six weeks depending on the dose and the sensitivity of the test used.
For workplace drug panels, testosterone is not part of standard five- or ten-panel urine screens. Those tests look for recreational drugs. You would only be tested for testosterone in sports anti-doping contexts or specific medical or legal situations.
What You’ll Feel as It Clears
The timeline for physical and psychological effects doesn’t perfectly match the pharmacokinetic timeline. Testosterone influences your body through a cascade of downstream processes, some of which continue even as blood levels start to drop.
In the first week after your last injection, you may still feel relatively normal as testosterone levels remain in a functional range. By the second week, many people notice the first signs of decline: reduced libido, lower energy, and changes in mood. Over weeks three and four, these effects become more pronounced. If you were on long-term therapy, your body’s natural testosterone production (which is suppressed during treatment) can take weeks to months to restart fully, depending on how long you were on TRT and your individual physiology.
Muscle and body composition changes happen on an even slower timeline. Gains in lean mass from testosterone therapy don’t disappear the moment the drug clears your system, but they will gradually diminish over months if natural testosterone production doesn’t recover to adequate levels.
Factors That Affect Clearance Time
- Dose size: A 200 mg injection leaves more testosterone to clear than a 100 mg injection, extending the tail end of the elimination curve.
- Duration of use: Months of regular injections build up tissue saturation, so clearance after long-term use takes longer than after a single shot.
- Injection site: Deeper intramuscular injections (like in the glute) tend to absorb more slowly than subcutaneous or shallow injections, potentially extending the release window slightly.
- Body composition: Testosterone cypionate is dissolved in oil, and individuals with higher body fat may metabolize the depot differently than leaner individuals.
- Metabolism: Liver function and overall metabolic rate play a role in how quickly the ester is cleaved and the testosterone is processed and excreted.
As a general rule, if you’re trying to estimate when Test C will be fully out of your system after your last injection, plan on roughly six weeks for a single dose and potentially eight or more weeks if you’ve been using it consistently for months.