Over-the-counterLower-cost generic available

Mucinex Dm

(Dextromethorphan / Guaifenesin)

  • Pill
  • Extended release
  • Liquid
Back to: Full Site NavigationSkip to: side effects sectionSkip to: What to expect sectionSkip to: Risks and warnings sectionSkip to: Tips from users and pharmacists

Breaks up mucus and relieves cough.

Skip Upsides & Downsides section. Skip to side effects section.
Over-the-counterLower-cost generic available

Our bottom line

Mucinex Dm (Dextromethorphan / Guaifenesin) is okay for loosening congestion in your chest and throat, but it could prevent you from coughing the mucus up. It comes as an extended-release tablet and a short-acting liquid.


  • Mucinex Dm (Dextromethorphan / Guaifenesin) is a combination medicine that relieves multiple cold symptoms. It's good to use if you have chest congestion and a cough.
  • Helps loosen the mucus and phlegm that builds up in productive and wet coughs.
  • The extended release version of Mucinex DM lasts up to 12 hours.


  • Mucinex Dm (Dextromethorphan / Guaifenesin) isn’t useful if you have a dry cough without mucus or phlegm.
  • The two medications in this product could potentially work against each other. Guaifenesin makes mucus easier to cough up, while dextromethorphan (the "DM" in Mucinex Dm (Dextromethorphan / Guaifenesin)) stops you from coughing.
  • Can cause sleepiness, dizziness, and an upset stomach.

Save on your next Mucinex Dm (Dextromethorphan / Guaifenesin) prescription

Get the lowest price for your medication, even if you have insurance.

What to expect when you take Mucinex Dm (Dextromethorphan / Guaifenesin)

Skip what to expect section. Skip to Risks & Warnings section.
Tips from our pharmacists
  • Cough suppressant starts working in 15 to 30 minutes.
  • Follow age-specific dosing instructions on how much to take. Don't take more than the recommended dose.
  • Drink plenty of fluids while taking Mucinex Dm (Dextromethorphan / Guaifenesin) because liquid helps break down mucus.
  • If your cough lasts more than 7 days, call your doctor.
Skip side effects sections. Skip to What to Expect and Pharmacists Tips section.

Side effects for Mucinex Dm (Dextromethorphan / Guaifenesin)

Filter group. All currently selected
Filter group. All currently selected

These are side effects of Mucinex Dm (Dextromethorphan / Guaifenesin) reported to the FDA by people taking it, and by doctors and pharmacists.

0 reports

Risks and Warnings for Mucinex Dm (Dextromethorphan / Guaifenesin)

Skip Risks and Warnings section. Skip to Tips section.
  • People taking Mucinex Dm (Dextromethorphan / Guaifenesin) have reported nausea and vomiting. This is very rare and usually not serious. If you develop a fever with the nausea and vomiting, then talk to your doctor right away.

Means that some groups have a high risk of experiencing this side effect

Tips from pharmacists and people taking Mucinex Dm (Dextromethorphan / Guaifenesin)

Final section. Do you want to return to drug navigation?
The FDA category for this medication is N. It is advised that you: Unknown
  • Last winter I had this problem where when I would lay down to sleep I would start coughing. I took this and 20 minutes later I laid down - no coughing. After a week or so the problem went away. Came back again later and this helped again.