I just started my first cycle of clen and am also prescribed propanalol(beta-blocker). I understand that clen desensitizes beta receptors and that's the reason for 2 weeks on and 2 weeks off. Do you guys know if beta blockers have a similar effect. I have been on propanalol for about 6 months now. Basically, my question is: can I use beta blockers during the 2 weeks off?