When to start post cycle therapy depends on what you were taking. The core rule is simple: wait until the compound has mostly cleared your system before beginning PCT. For long-ester testosterone, that means roughly 2 to 3 weeks after your last injection. For short-ester injectables and oral compounds, it can be as soon as a few days. For SARMs, you start immediately.
Getting this timing wrong in either direction undermines the entire point of PCT. Start too early and the suppressive compound is still active in your body, blocking the hormonal signals PCT is trying to restore. Start too late and you spend unnecessary time in a suppressed state with declining muscle mass, low energy, and disrupted mood.
Why Half-Life Determines Your Start Date
Every compound you take has a half-life, the time it takes for half the drug to leave your body. After one half-life, 50% remains. After two, 25%. After five half-lives, less than 3% of the original dose is still circulating, and that’s generally the point where your body can begin responding to PCT. The practical guideline is to wait approximately five half-lives after your last dose before starting.
This matters because PCT works by stimulating your pituitary gland to restart natural testosterone production. If significant levels of the suppressive compound are still in your bloodstream, the pituitary stays shut down regardless of what PCT drugs you take. With high dosages and long-acting esters, it can take a full month before recovery can even begin, because the compound simply hasn’t cleared yet.
Timing for Long-Ester Testosterone
Long-ester testosterone is the most common base of a cycle, and it requires the longest waiting period before PCT. Here’s what the timing looks like based on the specific ester:
- Testosterone enanthate has a half-life of roughly 5 to 7 days. Start PCT 10 to 14 days after your last injection.
- Testosterone cypionate has a half-life of about 12 days. Start PCT 14 to 18 days after your last injection.
- Sustanon-250 is a blend with the longest-acting ester driving the timeline. Its effective half-life is 15 to 18 days, so PCT should begin 18 to 21 days after the last injection.
If your cycle included nandrolone decanoate (often stacked with testosterone), the same principle applies, but nandrolone’s metabolites can linger in your system far longer than testosterone esters. In practice, cycles involving long-acting compounds should allow a minimum of 14 to 21 days before PCT begins.
During this waiting period, you won’t feel great. Testosterone levels are dropping but your natural production hasn’t restarted. This is normal and expected. Trying to rush PCT to avoid this window doesn’t help because starting a SERM while the ester is still releasing active hormone is essentially wasting it.
Timing for Short Esters and Oral Steroids
Short-acting compounds clear your body much faster, which means the waiting window shrinks significantly. Testosterone propionate, for example, has a half-life of less than two days. You can begin PCT roughly 3 to 4 days after your last injection.
Oral steroids like oxandrolone and methandrostenolone have half-lives measured in hours rather than days. For oral-only cycles, PCT typically starts immediately after the last dose or within a day or two. In clinical case documentation of cutting cycles lasting 8 weeks, PCT began in week 9, essentially right after the cycle ended.
If you ran an oral compound alongside a long-ester injectable, the injectable dictates your timeline. You always wait based on the longest-acting compound in your stack.
Timing for SARMs
SARMs follow a different rule than traditional anabolic steroids. Because most SARMs have short half-lives and clear the body quickly, PCT starts the day after your last dose. There is no waiting period.
The duration of PCT after a SARM cycle is typically four to six weeks, depending on how long the cycle lasted and how suppressive the specific compound was. Most people running standard-length cycles will need about four weeks. Compounds known for heavier suppression, like ligandrol, may warrant the full six weeks.
Where HCG Fits In
HCG is sometimes used during a cycle or in the bridge period between the last injection and the start of SERM therapy. It mimics the pituitary signal that tells the testes to produce testosterone, keeping them active while you’re waiting for the main compound to clear. But HCG itself is suppressive to the pituitary, which means it needs to stop before your SERM begins.
The handoff between HCG and SERM therapy is a detail many people get wrong. HCG has a short half-life of about 24 to 36 hours. You should begin your SERM 2 to 3 days after your final HCG injection. This gap lets the HCG clear so it isn’t actively suppressing the pituitary at the exact moment the SERM is trying to stimulate it. Running both simultaneously works against the purpose of each.
What Happens If You Time It Wrong
Starting PCT too early is the more common mistake. The SERM enters your system while the steroid ester is still releasing active hormone, creating a tug-of-war your SERM will lose. You burn through your PCT window without meaningful hormonal recovery, then come off the SERM still suppressed.
Starting too late is less harmful but still costs you. Every extra day spent in a suppressed state without intervention means more muscle loss, more fatigue, and a longer total recovery timeline. The goal is to hit the window where blood levels of the suppressive compound have dropped low enough that your pituitary can actually respond to stimulation.
If you used multiple compounds with different half-lives, always base your PCT start date on the longest-acting one. And if you ran unusually high doses, consider adding a few extra days to the standard timeline. Higher doses mean more total drug in your system, which takes longer to clear even though the half-life itself doesn’t change.