what is pct, or post-cycle therapy, describes the use of an anti-estrogen product following the use of a steroid cycle. After using steroids for an extended period of time, a few things happen in your body. First, your own natural levels of testosterone production have been severely impacted and there is a good chance you aren't producing any sperm, or at the very least aren't producing enough to procreate or maintain normal strength and libido levels.
Second, your body has been creating artificially high levels or estrogen to combat the artificial levels of testosterone. The estrogen will continue to be high, which can lead to some negative effects, the worst of which is gynecomastia. Finally, pct steroids are a good bridge to assist you in making the transition from minimal to normal testosterone production. Mostly a pct cycle deliver hormones which help to restart the testes, while at the same time delivering a small dose of testosterone to keep your own levels steady during this transition.
Most steroids have varying half-lives and active lives in the body, so the amount of time following your last dose, until PCT should be started, will vary. There is no universal window for PCT injection, and you want to get it as close as possible to the conclusion of your steroid's active life to ensure your body's natural levels of testosterone are elevated, and estrogen is negated.
If you're orally using Anadrol 50, a very potent and short-term drug, you'll want to begin a pct cycle just 24 hours after your last tablet. Likewise, your final Winstrol dose should be followed with PCT just one day after your final oral administration.
Injectable steroids last much longer in the body, so pct steroids should begin for them after a longer time period. You don't want to start PCT too soon, or you'll subject your body to stimulus before it is necessary and possible short-circuit the effects of your last shot. At the same time, waiting too long could cause a T crash and E spike - and nobody wants that.
Deca and Equipoise are perhaps the longest-lasting active steroids. You need to wait a full 21 days after your final shot to begin post-cycle therapy. Sustanon and Testosterone Cypionate each require 18 days, with Testosterone Enanthate and Primobolan only needing 14 days. Testosterone propionate and Fina only require 3 days of rest before PCT can begin. Finally, testosterone suspension joins Winstrol and Anadrol (and other orals) on the 24-hour injection list, as it's active life in the body is so short.
These times are only an approximation, and averages will have to be taken for those times when multiple compounds are being taken. Also, a user's experience, tolerance, size, constitution, and a wealth of other factors may play into this timing. These estimates are based upon the rate of speed in which the drug loses it's bio-availability and it no longer active in the bloodstream. Above all, follow any additional instructions listed on the individual PCT product. They may differ, and these differences may affect bio-availability as well. I hope this answer the question of what is pct.