Look at the folded paper, stapled to the professional white pharmacy bag, which instructs you on how to use the drug you just received. Or look at one of several websites which discusses various drugs or herbals that you might be taking. In either of these sources, did you notice, in addition to the “mechanism of action” and “how to use” sections, the “serious side effects” section? Every drug listed in the United States Pharmacopeia has side effects. And so do all the herbal medicines.