Arimidex is fine on cycle but it should not be used during pct as it will lose the majority of its effectiveness. Aromasin still works but it should only be used during pct if it is needed and only bloodwork or experience could tell you this. If estrogen is controlled the entire cycle until you transition into pct then most people won't need an AI during this time, as there will be little to no aromatizing steroids left to convert into estrogen to begin with. As the exogenous testosterone leaves your body where will the extra estrogen come from?
Your levels will be so low an AI might crash your estrogen which is not something you want. Especially during pct unless you used a large amount of long estered gear and are very prone to estrogenic side effects or gyno. Only experience and bloodwork can really tell you if aromasin is needed during pct. Although it can help with increasing testosterone, this is what Serms and HCG are for, which is also brings me back to why Arimidex shouldn't be used in pct..
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