I took Mucinex DM maximum strenth. BIG Mistake! About 10 hours later I felt like I was going to pass out. I was nauseated and dizzy. My pupils were extremely dilated. I was actually in my car on my way to work (as an ER Nurse) when this occured. I went to work and was hooked up to a cardiac monitor. My heart rate was in the 140's. NEVER EVER AGAIN!!