When to Start PCT After a Steroid Cycle: Clearance Times for 9 Compounds
When to Start PCT After a Steroid Cycle: Clearance Times for 9 Compounds
When to start PCT is decided by the ester, not the calendar. A SERM cannot restart the axis while exogenous androgen is still circulating at a suppressive level, so post-cycle therapy begins when the slowest compound in the cycle has cleared: two to three days after a short ester, about two weeks after enanthate or cypionate, three to four weeks after nandrolone decanoate, and six weeks or more after injectable undecanoate. This guide gives the half-life data behind each window, what happens when PCT starts too early or too late, and the bloodwork that confirms the timing for you rather than for the average man.
Educational and harm-reduction content. MuscleScience does not sell or supply any compound and does not provide dosing protocols for SERMs, hCG or anything else. Non-medical anabolic steroid use is illegal in most countries.
When to Start PCT: 3 Numbers That Set the Window
The wait that decides when to start PCT is not a tradition. It comes from measured pharmacokinetics: how long each ester keeps releasing hormone from the injection depot, and how long the axis stays switched off after the hormone is gone.
After a single 200 mg injection of testosterone cypionate in hypogonadal men, testosterone peaked on days 2 to 5, stayed above the normal range through day 7, and had fallen back to the untreated baseline by days 13 to 14 (Nankin 1987). That measured curve is the reason the two-week rule exists.
Injectable testosterone undecanoate in castor oil has a terminal half-life of 33.9 days (Behre 1999) and holds levels in range for 12 weeks per injection (von Eckardstein 2002). Five half-lives is about five months. No two-week rule applies; only bloodwork can time it.
In a urology cohort, prior anabolic steroid use was the single most common cause of profound hypogonadism (testosterone at or below 50 ng/dL), accounting for 43 percent of cases, and 21 percent of the clinic's whole hypogonadal population had a steroid history (Coward 2013).
The rule that follows from all three: the slowest ester in the stack sets the start date. Testosterone propionate is gone in days; the nandrolone decanoate injected alongside it is still suppressing the axis three weeks later. Timing from the fast compound and ignoring the slow one is the most common way a well-planned PCT achieves nothing.
Why PCT cannot start early: the feedback mechanism a SERM depends on, and why it is inert while androgen levels are still high.
Clearance times for 9 compounds, with the half-life data and the practical wait window for each.
The five-half-life rule, when it applies, and what changes it: dose, cycle length, body fat, stacking and age.
Too early versus too late, the bloodwork that confirms readiness, and the four timing mistakes that recur.
Why PCT Started Too Early Does Nothing
To understand when to start PCT, start with the mechanism. Exogenous androgens suppress the axis by negative feedback: the hypothalamus reads a high androgen and estrogen signal, slows GnRH pulses, the pituitary stops releasing LH and FSH, and the testes stop producing testosterone and sperm. Clomiphene and tamoxifen work on one half of that loop. They block estrogen receptors in the hypothalamus and pituitary, so the estrogen part of the feedback disappears and GnRH, LH and FSH rise. They do nothing about the androgen part. While a long ester is still releasing testosterone at a suppressive concentration, the axis stays down regardless of how much SERM is taken; the drug is consumed in a window where it cannot act. The mechanism is covered in full in why steroids cause testosterone suppression.
"End of cycle" and "cleared" are therefore different dates, and when to start PCT is tied to the second. After the last injection of enanthate or cypionate, serum testosterone stays supraphysiological for several days and above the suppressive level for roughly two weeks. Nankin's cypionate data show the whole shape: peak on days 2 to 5, above the normal range through day 7, baseline by days 13 to 14. A cycle can end on paper on a Friday and still be suppressing the axis on the following Friday. What PCT waits for is the second date. How the axis then rebuilds itself is the subject of hormonal recovery after steroids.
When to Start PCT by Compound: Half-Lives and Wait Windows
The when to start PCT table below uses half-lives from published pharmacokinetics (Nankin 1987, Behre 1999, Kicman 2008) and standard product data; the wait windows are the conventional harm-reduction practice derived from them. The compound with the longest ester in the cycle sets the date. Status reflects how long the axis stays suppressed after the last dose.
| Compound | Half-life | Five half-lives (about 97 percent cleared) | Typical PCT start after last dose | Status |
|---|---|---|---|---|
| Oral 17-alpha-alkylated steroids methandienone, oxandrolone, stanozolol | 3 to 9 hours | 1 to 2 days | 1 to 3 days. Clearance is fast; the depth of suppression after a long oral cycle is not. | ● Days |
| Trenbolone acetate | 1 to 2 days | 5 to 10 days | 2 to 3 days. Potent suppressor: expect deeper suppression than testosterone at equal duration. | ● Days |
| Testosterone propionate | 2 to 3 days | 10 to 15 days | 3 to 4 days | ● Days |
| Testosterone enanthate | 4 to 5 days | 20 to 25 days | 14 days; measured return to baseline at about 2 weeks after a single 200 mg dose | ● Two weeks |
| Testosterone cypionate | 5 to 6 days | 25 to 30 days | 14 to 18 days (Nankin 1987: baseline by day 13 to 14 after 200 mg) | ● Two weeks |
| Trenbolone enanthate | 5 to 7 days | 25 to 35 days | 14 to 18 days; bloodwork advisable because of suppression depth | ● Two weeks |
| Mixed testosterone esters propionate, phenylpropionate, isocaproate, decanoate blends | Set by the decanoate fraction: 7 to 10 days effective | 5 to 7 weeks | 18 to 21 days; the short esters in the blend are irrelevant to timing | ● Three weeks |
| Nandrolone decanoate | About 15 days | About 75 days | 3 to 4 weeks minimum, or stop it 4 to 6 weeks before the testosterone ends and time from the testosterone. Bloodwork before starting. | ● Weeks; verify |
| Testosterone undecanoate, injectable | 33.9 days in castor oil; 20.9 days in tea seed oil (Behre 1999) | About 5 months | 6 weeks as an absolute minimum, confirmed by bloodwork; a clinical dosing interval is 10 to 14 weeks (Bhasin 2018, Morgentaler 2008) | ● Months; verify |
Two rows need a note. The mixed-ester blends are sold on the promise of fast onset and long action, and the long action is exactly what matters here: the decanoate component keeps releasing for weeks after the propionate has gone. And injectable undecanoate is a replacement product, not a cycle product; anyone who has been on it and wants the axis back is in a months-long clearance window that no rule of thumb covers, and belongs with a clinician. For the difference between ester forms in general, see injectable vs oral steroids.
What Clearance Looks Like After the Last Injection
The chart shows the clearance figures that were actually measured in people. Testosterone cypionate was back at baseline 13 to 14 days after a 200 mg dose (Nankin 1987). Injectable undecanoate has a half-life of 33.9 days in castor oil and 20.9 days in tea seed oil (Behre 1999), and the pharmacokinetic study ran a 70 day dosing interval (Morgentaler 2008). Until the depot has emptied, the SERM is fighting it.
The spread is the real point: propionate is effectively gone inside two weeks, enanthate and cypionate inside three to four, nandrolone decanoate takes two and a half months, and undecanoate takes nearly half a year to reach the same 3 percent. The two-week convention is a reasonable compromise for enanthate and cypionate because the suppressive threshold is reached well before full clearance, at roughly three half-lives, which is where the measured cypionate curve returns to baseline. It is not a compromise that transfers to anything with a longer ester.
A different view: what is at stake if recovery is mishandled. Share of hypogonadal men whose condition traced back to prior anabolic steroid use, and share of users still hypogonadal after stopping.
Most men recover whatever they decide about when to start PCT; the HAARLEM cohort had average testosterone back at baseline three months after the cycle. The point of timing PCT properly is the tail: the men who do not, and who make up a startling share of the profound hypogonadism a urology clinic sees. Rahnema's 2014 review describes that outcome, anabolic steroid-induced hypogonadism, as dependent on dose, duration and compound type, which are exactly the variables the table above encodes.
4 Things That Move the PCT Start Date Off the Table Value
Half-lives are population means. Four factors move when to start PCT for an individual by shifting clearance or suppression away from the table, always in the direction of waiting longer or testing first.
Dose and injection volume
A half-life describes the rate of decline, not the starting point. A cycle at 1,000 mg a week starts its decline from a far higher serum level than one at 300 mg, so it stays above the suppressive threshold for more half-lives. Large oil volumes in one site also release more slowly than the same dose split across sites. High-dose cycles should treat the table window as a floor and confirm with bloodwork.
Cycle length and prior cycles
Clearance does not change with cycle length; suppression depth does. Twenty weeks of GnRH silence desensitizes the Leydig cells more than six, and each unrecovered cycle stacked on the last leaves less to recover with. This does not delay the start date, but it changes what to expect after it, and it is why the pre-PCT panel matters: LH and FSH near zero after a long history is a different starting point from the same numbers after a first short cycle.
Body fat and metabolism
Esterified testosterone is lipophilic and higher body fat extends the tail of release; liver function and individual enzyme activity shift the de-esterification rate. Published half-lives carry standard deviations of days for long esters (Behre's undecanoate figure was 33.9 plus or minus 4.9 days), which at five half-lives is a spread of weeks. Bloodwork replaces the estimate with the measurement.
Age and fertility plans
Axis responsiveness declines with age; men over 40 recover more slowly at any timing. And spermatogenesis is a separate clock: sperm count lagged testosterone by months in the HAARLEM cohort, and the classic contraceptive studies (Tom 1992) show how completely testosterone plus a GnRH antagonist can shut it down. Men with fertility goals should time PCT at the early edge of the window that pharmacokinetics allows and involve a reproductive endocrinologist. See fertility and suppression on steroids.
Starting PCT Too Early vs Too Late: What Each Looks Like
Too early is the common when to start PCT error. The SERM is started the day after the last enanthate injection, the axis is still suppressed by circulating testosterone, LH and FSH do not move, and by the time the ester has cleared two weeks later a chunk of the planned PCT has been used up doing nothing. The symptomatic gap that follows gets blamed on "PCT not working".
Too late is the rarer when to start PCT error, but real. After short esters, the crash from supraphysiological to near-zero happens over a few days; waiting two weeks "to be safe" after propionate leaves a man symptomatic and unsupported for ten unnecessary days, and after a long, deep cycle a stalled axis left alone for weeks is a stalled axis with a longer road back. The window for short esters is measured in days, and the pre-PCT panel tells you whether the axis has already begun to move on its own.
Total testosterone, LH and FSH drawn at the planned start date settle when to start PCT. Testosterone still well above the natural range means the ester has not cleared: wait. Testosterone low with LH and FSH at zero is the expected picture: start. LH and FSH already rising is a good sign the timing is right and the axis is responsive. Which markers, and how to read them, is covered in PCT bloodwork.
4 Mistakes in Deciding When to Start PCT
1. Starting the day after the last long-ester injection. Serum testosterone is still supraphysiological. Enanthate and cypionate need about two weeks; the measured cypionate curve is not back at baseline until day 13 to 14.
2. One wait window for every compound. Fourteen days is right for enanthate, ten days too long for propionate, and one to two weeks too short for nandrolone decanoate. The ester decides, not the compound class or the weekly dose.
3. Forgetting the nandrolone in the stack. Timing from the last testosterone injection while decanoate is still releasing means starting PCT under active suppression. Either stop the nandrolone four to six weeks before the testosterone, or time from the nandrolone and wait the extra weeks.
4. Deciding when to start PCT by calendar math without a blood draw. Half-lives are averages with wide spreads. One panel at the planned start date, with testosterone, LH and FSH, converts the estimate into a fact and catches both the man who clears slowly and the one whose axis is already restarting. The pre-cycle baseline that makes that panel interpretable is described in blood tests before steroids.
When to Start PCT: Common Questions
How long after my last injection should I start PCT?
When to start PCT depends on the ester of the slowest compound in the cycle: 2 to 4 days after propionate or trenbolone acetate, about 14 days after testosterone enanthate or cypionate, 18 to 21 days after mixed-ester blends, 3 to 4 weeks after nandrolone decanoate, and at least 6 weeks after injectable undecanoate, confirmed by bloodwork.
When should I start PCT after testosterone enanthate or cypionate?
When to start PCT after enanthate or cypionate: about two weeks after the last injection. After a single 200 mg dose of cypionate, testosterone was measured back at the untreated baseline by day 13 to 14, which is where the two-week convention comes from. High doses or large volumes can extend that; a blood test at day 14 confirms it.
When should I start PCT after Deca (nandrolone decanoate)?
Three to four weeks after the last nandrolone injection at minimum, because the decanoate ester has a half-life of about 15 days. The common alternative is to stop the nandrolone four to six weeks before the testosterone ends and then time PCT from the last testosterone injection.
When can I start PCT after an oral-only cycle?
One to three days after the last dose. Oral steroids have half-lives of hours, so they clear quickly; the suppression built up over a long oral cycle does not, so recovery can still take weeks and the same bloodwork applies.
What happens if I start PCT too early?
Nothing useful. While exogenous testosterone is still at a suppressive level, LH and FSH stay down no matter how much SERM is taken, and part of the planned PCT is spent with no effect. The symptomatic gap that follows is then misread as PCT failing.
Should I get bloodwork before starting PCT?
Yes: total testosterone, LH and FSH at the planned start date. High testosterone means the ester has not cleared; low testosterone with LH and FSH at zero is the expected starting picture; rising LH and FSH means the axis is already responding. It also records the suppression baseline for judging recovery later.
Does the wait change with a higher dose?
The half-life does not change, but the starting level does, so a high-dose cycle stays above the suppressive threshold for longer. Treat the table window as a minimum after heavy cycles and confirm clearance with a blood test rather than the calendar.
When should I start PCT after Sustanon or other ester blends?
About 18 to 21 days after the last injection. The propionate and phenylpropionate fractions clear in days, but the decanoate fraction keeps releasing for weeks and it is the slowest component that sets the start date.
References
Related PCT Guides
Final Educational Note
This when to start PCT guide discusses the pharmacokinetics of anabolic steroid esters and the timing of post-cycle therapy for educational and harm-reduction purposes. It is not medical advice, does not describe drug protocols, and does not replace consultation with a physician or endocrinologist. Half-lives quoted are published means; individual clearance varies.
MuscleScience does not sell or supply any compound. For the wider series, start at the PCT hub and the bloodwork and health hub. Author names are pseudonyms; see the About page and Disclaimer.
