Compare Mucinex DM vs. Benadryl

Head-to-head comparisons of medication uses, side effects, ratings, and more.

Mucinex Dm (Dextromethorphan / Guaifenesin)

Over-the-counter

Benadryl (Diphenhydramine)

Prescription or OTC
Breaks up mucus and relieves cough.

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.

5.4/ 7 average rating with 15 reviewsforMucinex DM
Treats allergy symptoms and helps you sleep.

Benadryl (Diphenhydramine) is great for allergies, but curl up on the couch after taking it and get ready for a nap.

5.6/ 7 average rating with 294 reviewsforBenadryl
Upsides
  • 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.
  • Benadryl (Diphenhydramine) is often better than other antihistamines at treating allergy symptoms and hives.
  • It can provide quick relief of allergy symptoms for both kids and adults.
  • It makes you sleepy, so it'll help if your allergies are bothering you at night.
  • The effects wear off in 4 to 6 hours, so side effects don't last that long.
  • It comes as a tablet, capsule, liquid, and quick dissolving tablet.
Downsides
  • 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.
  • Benadryl (Diphenhydramine) makes you more tired than Claritin, Allegra, or Zyrtec.
  • You shouldn't drive after taking Benadryl (Diphenhydramine) until you know how it affects you.
  • Talk to a pediatrician before giving Benadryl (Diphenhydramine) to a child.
  • It can increase the risk of falls, so elderly people shouldn't use Benadryl (Diphenhydramine).
  • Don't use Benadryl (Diphenhydramine) if you are breastfeeding.
Used for
Dosage forms
  • Pill
  • Extended release
  • Liquid
  • Pill
  • Oral solution
  • Cream, gel, or ointment
No pricing information available
No pricing information available
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Reviews
15 
73%
think this treatment is worth it
73%
think this treatment works well
13%
think this treatment is a hassle

Have you used Mucinex Dm (Dextromethorphan / Guaifenesin)?

Leave a review
294 
86%
think this treatment is worth it
59%
think this treatment works well
8%
think this treatment is a hassle

Have you used Benadryl (Diphenhydramine)?

Leave a review
Side effects
The Mucinex Dm (Dextromethorphan / Guaifenesin) FDA package insert doesn’t have numbers about how common side effects are.
The Benadryl (Diphenhydramine) FDA package insert doesn’t have numbers about how common side effects are.
Risks and warnings
  • Serotonin syndrome

    Using other medications that affect serotonin

See more detailed risks and warnings
  • Overdose

    Using other drugs with the same ingredients

  • Increased side effects

    Age 65 years or older

  • Driving impairment

    Taking with alcohol

    ...and 1 more risk factors

  • Hyperactivity

    Children age 6 years and younger

  • Trouble urinating

    Enlarged prostate

    ...and 1 more risk factors

  • Vision changes

    Glaucoma

  • Breastfeeding

    Nursing mothers

See more detailed risks and warnings