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Mucinex and Drowsiness: What Users Say

Drowsiness: mentioned by 8 users (5.2%)

Based on user experiences from 155 Mucinex reviews, the following table shows the most commonly mentioned side effects.

All user comments are moderated by Drugs.com. Each review is verified for relevance and screened for inappropriate content. Side effects are user-reported and not clinically verified.

cough 6.5%
nausea 5.8%
drowsiness 5.2%
diarrhea 3.9%
dizziness 3.2%
vomiting 3.2%
headaches 2.6%
insomnia 2.6%
pain 2.6%
mucus 1.9%

Reviews for Mucinex

Showing 8 reviews tagged with "drowsiness". Clear filters to view all 155 reviews.
Commonly mentioned side effects
  • Anonymous
  • October 13, 2009

For Bronchitis "First time Mucinex DM user. I like the extended relief because it really does provide extended relief from the severe coughing that is characteristic of bronchial infections. The medication did make me a little drowsy, so some caution is recommended especially if you are not able to take time off to rest. I also recommend drinking lots of fluid too. You may notice that your urine smells like the medication."

9 / 10
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  • jim...
  • October 15, 2014

For Cough "After all the treatments I had from the doctor, nothing really suppressed the cough, which I have had for years. After taking Mucinex, my cough and the associated phlegm have almost disappeared. I am a 74-year-old male, but my side effects seem to be the opposite of others, i.e. I am doing more sleeping than normal, at any time night or day, but thank heavens for the cessation of cough."

9 / 10
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90 Report
  • Anonymous
  • November 7, 2011

For Cough "About an hour and a half after taking one Mucinex DM, I developed severe dizziness, drowsiness, bad intestinal cramps, vomiting, and diarrhea that recurred over a period of 2 hours. It was the only medication in my system."

1 / 10
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54 Report

Frequently asked questions

  • tom...
  • Taken for less than 1 month
  • September 23, 2021

"I took this for muscle pain and soreness, which is a common off-label use recommended by my doctor. While it was pretty effective for relaxing muscles, it caused very bad sleeplessness, even when taking an Ambien. I had to stop use, as insomnia made the muscle pain worse! Catch-22..."

3 / 10
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4 Report
  • Anonymous
  • August 29, 2009

For Bronchitis "This is the only medicine that helps loosen nasal mucus without the side effects like sleepiness or jitters that most of the sinus medications give me. It's great!"

9 / 10
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62 Report

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  • Dil...
  • Taken for less than 1 month
  • July 17, 2014

For Cough "The side effect was sleeplessness. First night, I was up until 4:00 AM, next night up until 07:00 AM, and again last night I could not sleep. I was taking the Mucinex as prescribed every 12 hours."

8 / 10
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42 Report
  • agr...
  • December 31, 2014

For Cough "My cough was so bad that I now have an umbilical hernia, but the Mucinex worked. I only took it in the morning because it did cause sleeplessness."

9 / 10
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34 Report
  • Sol...
  • March 17, 2020

For Bronchitis "I took Mucinex about a month ago, and it had me sleeping all day, extra, extra tired with a slight fever. It's not my thing."

1 / 10
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Reviews may be edited to correct grammar/spelling or remove inappropriate content. Reviews appearing to come from parties with a vested interest are not published. This information is not intended to endorse any medication and should not replace the expertise and judgment of healthcare professionals.