Yes agree with arnold jr, ECA stacks are less effective and make you feel worse. Ramp up slow like AJ said, this most recent time i used clen i ramped up kinda fast and felt pretty jittery the first few days till my body aclimated. Also did notice that my body seems to have adapted some to the clen this second go around, as its taking about 40 mcg more to get the same effect this time. im up to about 120mcg ED