I have taken ephedrine before smoking in order to prevent myself from burning out and just going to bed early, and yeah, I noticed when the ephedrine kicked in it kinda sucked. I only take it after i smoke now so it doesnt clash as bad.

Ephedrine rocks though if you ever need a quick and legal boost of energy. Just don't get hooked or it kinda thins your bones out or something over a long time and you break them easier, I dunno.