Mucinex D vs Mucinex DM: What’s the Difference?

Mucinex D (guaifenesin and pseudoephedrine) and Mucinex DM (guaifenesin and dextromethorphan) are cough and cold products that contain two active ingredients each.

Both products have the active ingredient guaifenesin, which loosens phlegm and makes it easier to cough out.

They differ because Mucinex D also contains pseudoephedrine, a nasal decongestant, while Mucinex DM contains dextromethorphan, a cough suppressant.

Also, Mucinex DM is available over-the-counter (OTC), while Mucinex D is sold behind the counter, requires ID, and can only be purchased in limited quantities without a prescription.

This article discusses the similarities and differences between Mucinex D and Mucinex DM.

Mucinex D vs Mucinex DM: What Are They and How Do They Work?

Mucinex D contains guaifenesin, an expectorant, and pseudoephedrine, a nasal decongestant.

The guaifenesin helps loosen phlegm and thin secretions in the lungs to clear the bronchial passageways of mucus and make coughs more productive.

The pseudoephedrine works by causing vasoconstriction to temporarily relieves nasal congestion, restore free breathing through the nose, promote nasal and/or sinus drainage, and relieve sinus congestion and pressure. A product containing a D after the name, such as Mucinex D, usually has a decongestant (e.g., phenylephrine or pseudoephedrine).

Mucinex DM also contains guaifenesin, an expectorant, and dextromethorphan, a cough suppressant, in each tablet.

The guaifenesin helps loosen phlegm and thins bronchial secretions to clear mucus and make coughs more productive, while the dextromethorphan suppresses the intensity of coughing and reduces the impulse to cough.

Dosage Strengths and Forms

Mucinex D is available as an oral extended-release (ER) tablet. Depending on the dosage strength, it is recommended to take either one (1,200 milligrams/120 milligrams tablet) or two (600 milligrams/60-milligram tablet) every 12 hours. Because of its design, tablets must not be cut, crushed, or chewed.

Mucinex DM is available as an oral ER tablet. Depending on the dosage strength, it is recommended to take one (1,200 milligrams/60 mg tablet) or two (600 mg/30 mg tablet) every 12 hours. Like Mucinex D, these tablets must not be cut, crushed, or chewed.

Mucinex DM is also available as an oral solution. It is marketed under Mucinex Fast-Max DM in cherry and honeyberry flavors. Each 20 milliliter contains 400 milligrams of guaifenesin and 20 milligrams of dextromethorphan.

Mucinex D vs. Mucinex DM: Side Effects

Mucinex D and Mucinex DM are generally well tolerated at recommended doses. Side effects can occur, although you may not have any.

Common side effects that may be experienced with both Mucinex D and Mucinex DM include:

• Dizziness
• Drowsiness
• Nausea or vomiting
• Headache
• Rash

When taken at higher doses, Mucinex D and Mucinex DM can also cause kidney stones.

Mucinex D

Other side effects that may be experienced with Mucinex D include:

• Anxiety 
• High blood pressure 
• Insomnia
• Heart palpitations 
• Tremor 
• Urinary retention

Serious side effects that may be experienced with Mucinex D include:

• Irregular heartbeat
• Hypertension
• Severe skin reaction

Mucinex DM

Other side effects that may be experienced with Mucinex DM include:

• Constipation
• Stomach pain
• Fatigue 

Serious side effects that may be experienced with Mucinex DM include:

• Abuse/dependence
• Serotonin syndrome
  

Drug-Drug Interactions

Mucinex D and Mucinex DM should not be taken within 14 days of taking medications called monoamine oxidase inhibitors (MAOIs), such as:

• Isocarboxazid
• Tranylcypromine
• Phenelzine
• Selegiline

When used with pseudoephedrine, MAOIs can increase the risk of severely high blood pressure. MAOIs can also interact with the dextromethorphan in Mucinex DM, potentially leading to serotonin syndrome.

Safety Warnings

While generally safe, these medications may not be appropriate in some situations.

Mucinex D contains a decongestant, so be cautious about using it and discuss it with your healthcare provider if you:

• Have heart disease
• Have uncontrolled high blood pressure
• Have diabetes
• Have hyperthyroidism
• Have bowel obstruction
• Have glaucoma
• Have benign prostate hyperplasia (enlarged prostate)
• Are older than 65 years

Mucinex DM might not be appropriate for these populations.

Due to limited research, the safety of these products when used during pregnancy has not been established. Healthcare providers may recommend avoiding taking guaifenesin in the first trimester of pregnancy unless the benefits outweigh the potential risks.

Stop taking the medication and contact your healthcare provider if your symptoms do not improve within seven days, recur, or occur with a fever, rash, or persistent headache.

Which One Is Right for You?

If you are experiencing a cough, deciding between Mucinex D and Mucinex DM may be a tough choice. Since these products contain guaifenesin, they help reduce chest congestion to move phlegm upwards and out.

Mucinex D is appropriate for productive coughs with sinus congestion or a stuffy nose. The guaifenesin helps loosen phlegm and make coughs more productive, while the pseudoephedrine relieves nasal congestion, promotes nasal and/or sinus drainage, and relieves sinus congestion and pressure.

Mucinex D contains a decongestant, so it should be used cautiously in those with heart disease or uncontrolled hypertension (high blood pressure), diabetes, hyperthyroidism, bowel obstruction, glaucoma, benign prostatic hyperplasia (BPH), and those 65 and older. Mucinex DM may be a more appropriate option in these populations.

Mucinex DM is more suitable for dry, unproductive cough or to suppress productive cough at night to allow for restful sleep, since the cough-suppressing effects persist for five to six hours after ingestion.

Summary

Mucinex D and Mucinex DM are cough and cold products containing guaifenesin to loosen phlegm.

Although both Mucinex D and Mucinex DM are practical options for cough relief, deciding which one is best for you might depend on your cough type and other factors, including coexisting health conditions.

Mucinex D has pseudoephedrine and relieves productive coughs with congestion, while Mucinex DM contains dextromethorphan and helps relieve dry or unproductive coughs. Dextromethorphan–a cough suppressant–can cause hallucinations and euphoria at high doses, which increases the risk of abuse and dependence.

Because it contains pseudoephedrine–which can be used to produce meth–Mucinex D requires an ID to purchase, whereas Mucinex MD is available OTC.