How Long Does Testosterone Stay Detectable?

One of the most common questions about injectable testosterone is also one of the most misunderstood: how long after my last dose can a drug test still detect it? The answer depends less on the testosterone itself and more on the metabolites your body produces, and those linger far longer than most people expect.

The ester changes everything

The ester attached to testosterone controls the release rate, and different esters produce different long-lived metabolites at different concentrations. This is why Testosterone Propionate clears in weeks while Testosterone Enanthate can trigger a positive test months later.

Why metabolites, not testosterone, set the window

Anti-doping labs (WADA-accredited) do not test for testosterone directly, your body produces it naturally. Instead they look for marker metabolites that only appear when synthetic testosterone has been administered:

• Epimetendiol (17β-hydroxymethyl-androstane), the long-lived marker for testosterone enanthate and cypionate, detectable via GC-MS/MS for roughly 2–3 months after the last dose.
• The T/E ratio (testosterone to epitestosterone), a screening flag, though it normalizes faster than the metabolite markers.

This is why “it cleared my system in a week” is almost always wrong: the hormone may be gone, but the metabolite fingerprint persists.

The ester-by-ester breakdown

Testosterone enanthate and cypionate

The two most common TRT and cycle esters share essentially the same detection profile. The epimetendiol metabolite is detectable for 60–90 days post-last-dose via GC-MS/MS. A 12-week cycle of Testosterone Enanthate means the window closes roughly 3 months after your final injection, sometimes longer with high cumulative doses.

Testosterone propionate

The short-acting propionate ester normalizes the T/E ratio faster, typically 2–3 weeks, because it produces a smaller, briefer metabolite load. It’s the shortest-window injectable testosterone, but it is not “undetectable in days” as folklore sometimes claims.

Testosterone undecanoate (Nebido)

The very-long-acting Nebido formulation produces a metabolite tail that can stretch the window considerably, consistent with its 30+ day half-life and the slow depot release.

What actually affects your window

Four factors dominate, in roughly this order:

1. Cumulative dose and duration, a 16-week cycle at 500 mg/week leaves a longer fingerprint than a single 100 mg TRT dose.
2. The specific metabolite, nandrolone’s 19-norandrosterone persists for up to 18 months, making it the longest-window AAS by a wide margin.
3. Individual metabolism, liver enzyme activity, body composition, and genetics all shift the timeline.
4. The assay, modern LC-MS/MS and GC-MS/MS are far more sensitive than older immunoassays, extending windows.

The bottom line

If you are subject to anti-doping testing, the relevant question is never “when does the drug leave my bloodstream”, it is “when do the marker metabolites fall below the detection threshold.” For testosterone enanthate and cypionate, that is roughly three months. For nandrolone, it can exceed a year. Plan accordingly, and work with a qualified medical professional rather than guessing.

WADA Technical Document TD2024ISLR ^[src] JCEM testosterone ester pharmacokinetics ^[src]