Most athletes and users think in terms of half-lives — how long a compound "feels active." Anti-doping laboratories work entirely differently. They track long-term metabolites that persist in urine, blood and hair long after the active compound has cleared. Modern testing has extended detection windows dramatically: compounds previously thought to clear in days now test positive for weeks; nandrolone-based compounds can remain detectable for 9–18 months. This guide covers every major compound class with current detection data, the science behind why detection outlasts pharmacological effect, and what IRMS testing means for testosterone users specifically.
Understanding esters and half-lives? See: Injectable vs Oral Steroids — Complete Guide.
Half-Life vs Detection Time — The Critical Difference
These two concepts are fundamentally different and confusing them is the most common error in planning around drug testing:
| Concept | Definition | Example |
|---|---|---|
| Half-life | Time for active drug concentration in blood to reduce by 50% | Testosterone Enanthate: 7–10 day half-life — active compound reduced by half every 7–10 days |
| Detection time | How long any metabolic trace — including inactive metabolites — can be found in a biological sample | Testosterone Enanthate: detectable for 3–5+ weeks in urine via standard methods; longer via IRMS |
| Pharmacological effect | How long the compound produces meaningful anabolic effect | Testosterone Enanthate: meaningful anabolic effect for approximately 2–3 weeks after last injection |
The gap between "feeling clear" and "actually clear" is large — and has grown larger as laboratory methods have improved. A compound that feels inactive after 2 weeks can produce a positive test 6+ weeks later from metabolite accumulation.
How Modern Anti-Doping Testing Works
Understanding what labs actually test for explains why detection times keep extending as technology improves:
Metabolite Testing
When the body processes an AAS compound, it creates breakdown products — metabolites. Modern labs do not look for the parent compound — they look for specific metabolites that are unique to that compound and persist in urine far longer than the active drug. The discovery of new long-term metabolites for compounds like stanozolol, oral Turinabol and nandrolone has retrospectively extended detection windows beyond what older charts reported.
IRMS — Isotope Ratio Mass Spectrometry
Testosterone deserves special mention because it is produced naturally. Standard testing looks at the testosterone-to-epitestosterone (T/E) ratio — above 4:1 triggers further investigation. IRMS goes further: it analyses the carbon isotope ratio of testosterone metabolites. Synthetic testosterone has a slightly different carbon-13 to carbon-12 ratio than natural testosterone. IRMS can identify synthetic testosterone even when T/E ratio appears normal — making older "timing" strategies unreliable.
WADA Prohibited List
The World Anti-Doping Agency (WADA) maintains the prohibited list and sets the analytical standards for testing. All AAS, SARMs and most performance peptides are on the prohibited list. WADA laboratories continually develop new detection methods — the list of detectable compounds and the precision of detection both expand every year.
Injectable Steroids — Detection Windows
Very Long Detection — Months
| Compound | Ester | Approx. Detection Window | Notes |
|---|---|---|---|
| Nandrolone Decanoate (Deca) | Decanoate | 9–18 months | Longest detection of common AAS — nandrolone metabolites (19-norandrosterone) persist extremely long |
| Nandrolone Phenylpropionate (NPP) | Phenylpropionate | 8–12 months | Shorter ester than Deca but same nandrolone metabolites — detection still very long |
| Boldenone Undecylenate (EQ) | Undecylenate | 4–6+ months | Long-term metabolites discovered relatively recently — older charts significantly underestimated |
| Methenolone Enanthate (Primobolan) | Enanthate | 3–5+ months | Often assumed "safe" — wrong. Long-term metabolites extend detection well beyond half-life |
| Trenbolone Enanthate | Enanthate | 8–12+ weeks | Long-ester Tren — metabolites persist significantly longer than half-life suggests |
Long Detection — Weeks to Months
| Compound | Ester | Approx. Detection Window | Notes |
|---|---|---|---|
| Testosterone Enanthate | Enanthate | 3–5+ weeks (IRMS longer) | Standard urine: 3–5 weeks. IRMS can extend effective detection significantly |
| Testosterone Cypionate | Cypionate | 3–5+ weeks (IRMS longer) | Equivalent to Enanthate in detection terms |
| Sustanon / Testosterone blend | Multi-ester | 4–10+ weeks | Different esters clear at different rates — detection window extends to longest ester in blend |
| Trenbolone Acetate | Acetate | 4–8 weeks | Short ester but significant metabolite accumulation with repeated use |
| Drostanolone (Masteron) | Propionate/Enanthate | 2–4+ weeks | Shorter detection than most injectables — but not as short as commonly assumed |
| Stanozolol injectable | Water-based | 3–6+ weeks | Same metabolites as oral Winstrol — see oral table below |
Shorter Detection — Days to Weeks
| Compound | Ester | Approx. Detection Window | Notes |
|---|---|---|---|
| Testosterone Propionate | Propionate | 10–20 days | Shorter detection than long esters — but IRMS still applicable |
| Testosterone Suspension | No ester | 3–14 days | Fastest-clearing testosterone — but IRMS can still detect synthetic origin |
Oral Steroids — Detection Windows
Oral steroids were historically underestimated for detection time. The discovery of long-term metabolites for stanozolol, oral Turinabol and oxymetholone has extended their windows significantly beyond older charts.
| Compound | Slang | Approx. Detection Window | Notes |
|---|---|---|---|
| Chlorodehydromethyltestosterone | Tbol / Turinabol | 6–12+ weeks | Dramatically extended after long-term metabolite discovery — older charts said 6 weeks; now 12+ weeks documented |
| Stanozolol | Winstrol / Winny | 3–9+ weeks | Long-term metabolites extend detection significantly beyond half-life; injectable form similar window |
| Methandrostenolone | Dianabol / Dbol | 3–6 weeks | Metabolites persist in urine well after compound clears blood |
| Oxymetholone | Anadrol / A-bombs | 3–8 weeks | Strong anabolic — metabolites accumulate with higher doses |
| Oxandrolone | Anavar / Var | 3–6 weeks | Considered "mild" pharmacologically but detection window is not shorter than other orals |
| Fluoxymesterone | Halotestin / Halo | 2–5 weeks | Potent oral with moderate detection window |
| Methyldrostanolone | Superdrol / SDrol | 6–8 weeks | Relatively long detection for an oral — metabolites persist |
SARMs — Detection Windows
SARMs are on the WADA prohibited list and detection methods have improved substantially since their initial appearance on the market. Being non-steroidal does not mean undetectable — WADA has invested significantly in SARM detection technology.
| Compound | Code | Approx. Detection Window | Notes |
|---|---|---|---|
| Ligandrol | LGD-4033 | 3–4+ weeks urine | Glucuronide metabolites detectable in urine — WADA validated method exists |
| Ostarine | MK-2866 | 2–3+ weeks urine | Smallest detection window of commonly used SARMs — still weeks, not days |
| S23 | S23 | 3–5+ weeks | Limited public detection data — assume similar to LGD-4033 |
| YK-11 | YK-11 | 3–4+ weeks | Structural similarity to steroids — detected by steroidal methods as well as SARM-specific tests |
| Ibutamoren | MK-677 | Detection varies — on WADA list | Not a SARM but on prohibited list. Detection methods exist but public data limited |
| Cardarine | GW-501516 | 40+ days documented | Specific WADA-validated detection method — long-term metabolites documented in peer review |
Peptides — Detection Status
Performance peptides present unique detection challenges — most have short half-lives and are present in low concentrations, making detection technically difficult. However WADA's detection capability has improved significantly:
| Peptide Class | WADA Status | Detection Capability |
|---|---|---|
| GH secretagogues (Ipamorelin, CJC-1295, GHRP-2/6) | Prohibited | WADA-validated methods exist — urine detection window 12–24 hours after dosing for most |
| IGF-1 / IGF-1 LR3 | Prohibited | Detectable in blood — short window due to short half-life; isoform differential assay used |
| Tesamorelin | Prohibited (GHRH analogue) | Detectable — short window but validated method exists |
| BPC-157 / TB-500 | Prohibited | Detection methods exist but less standardised — short detection window |
| Melanotan II / PT-141 | Not explicitly prohibited (not specifically listed) | Not on WADA prohibited list as of 2025 — status may change |
| Tirzepatide / GLP-1 agonists | Not prohibited | Not on WADA prohibited list — used medically for obesity |
For a full guide to peptides: Best Peptides for Muscle Growth and Recovery.
Testosterone and IRMS Testing
Testosterone requires specific discussion because it is produced naturally — standard concentration testing alone cannot identify exogenous use in many cases.
T/E Ratio
The testosterone-to-epitestosterone ratio is the standard screening method. The threshold is typically 4:1 — above this triggers IRMS investigation. However natural T/E varies between individuals and some users have naturally elevated ratios, meaning this test can produce false positives or miss users who use doses that keep their ratio under threshold.
IRMS — The Carbon Isotope Method
Isotope Ratio Mass Spectrometry analyses the carbon-13 to carbon-12 ratio in testosterone metabolites. Synthetic testosterone derived from plant sources (soy, yam) has a slightly different isotope ratio than endogenous testosterone. IRMS can identify synthetic testosterone even when:
- Total testosterone levels are within normal range
- T/E ratio appears normal
- Dose was low enough to avoid concentration-based detection
IRMS effectively removes the "timing" strategy from testosterone users — the isotope ratio persists in metabolites for weeks beyond the point where standard methods would be negative.
Factors That Extend Detection Beyond Standard Estimates
Detection time estimates are approximate — multiple factors can push real-world detection significantly longer:
| Factor | Effect on Detection |
|---|---|
| Higher doses | More metabolites produced and stored — excretion takes longer |
| Longer cycle duration | Metabolite accumulation over time extends excretion phase |
| Higher body fat | Some lipophilic compounds store in adipose tissue — released slowly as fat is mobilised |
| Slower metabolism | Individual metabolic rate affects excretion speed — age, kidney function, hydration |
| Advanced laboratory technology | Detection limits improve every year — compounds that "cleared" at old sensitivity levels may now test positive |
| Retesting frozen samples | WADA stores samples for 10 years — samples that were negative with old methods may be retested with new methods |
| Compound stacking | Multiple compounds produce multiple metabolite streams — each with its own excretion timeline |
Testing Matrices — Urine, Blood, Hair
Detection time depends significantly on which biological sample is tested:
Urine — Primary Matrix
Urine testing is the primary anti-doping matrix and provides the longest detection windows for most AAS. Metabolites concentrate in urine as the kidneys filter them from blood. Nandrolone's 9–18 month window is a urine detection time — blood detection would be much shorter.
Blood — Shorter but Useful
Blood testing detects recent use and specific hormones (GH, IGF-1) that are better measured in blood than urine. Detection windows in blood are generally shorter than urine for AAS but blood is the primary matrix for GH and IGF-1 detection.
Hair — Long-Term History
Hair testing reflects a historical record of drug use — approximately 1 cm of hair growth represents one month. A 3 cm hair sample can indicate drug use patterns over the previous 3 months. Hair testing is less common in sports anti-doping but is used in workplace testing, legal proceedings and some sports organisations.