When taking 2 Sudafed doesn't work, do not take 2 more an hour and a half later. You will definitely be able to breathe, however, your eyes will dilate, your hands will shake and you won't be able to stand upright. I unfortunately did this about an hour before leaving work and was unable to get home on my own. I'm home and have detoxed to the point of not being able to breathe again. Only two more hours until I can pop open the Nyquill bottle. I promise no matter what, I will only take the allotted dosage.