yes, you either take an estrogen blocker or an estrogen inhibitor. A blocker will attach to receptors so the free estrogen has nowhere to attach itself, this still leaves ur estrogen levels high, an inhibitor helps prevent estrogen completely and will drop the overall levels down to a point that a blocker is not necessary. old school thought was take both to ensure gyno prevention, but this is incorrect. some blockers/inhibitors are not able to be run concurrently and one will break down the plasma of the other in the blood. since these drugs are typically somewhat expensive, its nice to not throw away hundreds of dollars. I prefer inhibitors, but they do hinder gains a tad. I just prefer to keep the water retention down while on, and would swap that for a few more sloppy pounds anytime. | 
