cough and nasal congestion
"It dehydrates you like crazy and I could not drink enough liquids.  My throat got so dry it caused me to cough uncontrollably.  For the past 3 nights I could not sleep... Even took 10mg of Ambien which usually knocks me out cold.... But it didn't work.  I just found this site and learned that my insomnia is caused by mucinex d.  Not worth the lack of sleep!"