I am not sure exactly why but I can imagine it might increase the symptoms of the asthma, I would advise you to stay away and follow the directions on the label
I may be due to the ephedrine as well. Both my bottles of Adipokinetix and Pure Ephedrine HCL say not to use the product if you have asthma problems as well
Ephedrine is given to asthma patients, since it is a beta-2 agonist it acts as a bronchiol dialator, and actually helps u breath. Most of these products have warnings just to protect the companies ass from a lawsuit.