Cough
"I have been suffering from a severe sinus infection for 6 weeks.  Antibiotics twice, 3 trips to Dr.  When I was at my sickest, I was using MucinexD and it may have helped some.  I felt so bad then I don&#039;t know that I would have noticed side effects.  But weeks later, I was still having so much thick drainage and light headed in my throat that my Dr. told me to switch to the Mucinex (plain) thinking it was the pseudoephedrine that was causing the vertigo.  My vertigo worsened and I never even thought of the medication being the cause because the Dr. had said I would be fine without the pseudoephedrine in it.  Went to ER when my vertigo became alarming.  All tests negative.  After all that I found I am allergic to Guaifenesin."