There is no rebound.When using SERMS,the estrogen is always in production and circulation,it's just being inhibited from binding to certain sites.When the SERMS are discontinued,the estrogen that is still freely circulating is now free to bind with those sites that were once occupied and deactivated.With aromitase inhibitors such as anastrozole,femara,cytadren,etc.,the ezyme responsible for the CREATION of estrogen is down regulated in the testes.This leads to a less proficient ability for the body to produce estrogen,and circulating populations slowly wane.Due to it being an ENZYMATIC reaction,this effect is long lasting.It takes the body a while to start cranking out the aromitase again,particularly if your anti-aromitase is ran well past your active A/S.