For OTC cough syrup, I use Delsym (Dextromethorphan polistirex) or Mucinex (Guaifenesin). I've never had a problem with either, and I'd consider myself fairly sensitive to cold medications. When I need the big guns, I get my PCP to prescribe Tussionex (chlorpheniramine and hydrocodone) aka. "Liquid Gold". I love this stuff. It's expensive, hence the name. But you WILL stop coughing, and you WILL sleep! I nursed my last bottle thru 2 cold seasons finally cutting open the plastic bottle, and literally licking the sides of it clean. The stuff is amazing, and for some reason, this type of antihistamine doesn't bother me like others do.