Cough and Nasal Congestion
"I take mucinex D 600/60mg every morning for chronic sinus issues. It has helped considerably with sinus headaches. I would not recommend taking the 1200 mg strength, nor should you take 2 of the 600 unless it is EARLY in the morning... and only for a couple of days.  The 1200mg strength has 120mg of long acting sudafed... that is too much from my experience. DO NOT take this med after say 12 noon.  It will keep you awake for at least 8 hrs!  ALSO if you take this long term... it is not something you want to quit suddenly... wean yourself off to prevent irritability, etc."