epi has an effects estrogen in a way similar to nolva...but it has a half life of only six hours....so it can cause drastic fluctuations in free estro....thus causing gyno...but at the same time within the half life of the compound it does suppress estrogen so it can get rid of some peoples gyno as well....if your gonna do it i would run it alongside 10mgs of nolva a day so you dont get the estrogen flux