wow so after reading all of these posts I now realise that its not just ME and I'm not going crazy. I just started takeing Guaifenex the other day because I have alot of mucas in my lungs and a stuffy nose due to a cold. I was a little scared to take it at first because the over the counter mucus relief medicines made me sick to my stomach but I felt as though takeing Guaifenex was my only hope to actually get sleep at night....um I was wrong. Yes my mucus completely went away for the night but I found myself up for hours watching reruns of safe by the bell. I've felt very funny not knowing why, Dizzy, nervous, panicky, talking really fast, EXTREMELY hyper. Worse then if I drank coffee. Today is my third day takeing it and unfortunately I took my next dose right before I found this website and even thought too look up anything about it. I suggest takeing it during the day if you MUST take it, but I really do not recommend it at all. Try Afrin but only use it exactly as directed or you'll get more mucas problems then you had in the first place, its over the counter and seems a little more safe.
Thumbs down on this one.