Guaifenesin/dextromethorphan is a combination medication that is an expectorant and cough suppressant.

• Robitussin DM Maximum Strength (liquid),
• Robitussin DM Maximum Strength (capsules),
• Mucinex DM,
• Mucinex DM Maximum Strength,
• Mucinex Fast-Max DM

Yes

No

Guaifenesin and dextromethorphan temporarily relieve cough due to minor throat and bronchial irritations that are associated with cold. Guaifenesin/dextromethorphan also help loosen mucus and thin bronchial secretions.

Side effects of guaifenesin and dextromethorphan are:

• nausea,
• vomiting,
• constipation,
• drowsiness, and
• dizziness.

Adults and children 12 years of age and older:

• Robitussin DM and Robitussin DM Maximum Strength (liquid): Take 10 ml by mouth every 4 hours as needed. No more than 6 doses in 24 hours.
• Mucinex Fast-Max DM: Take 20 ml by mouth every 4 hours. No more than 6 doses in 24 hours.
• Robitussin DM Maximum Strength (capsules): Take 2 capsules by mouth every 4 hours as needed. No More than 12 capsules in 24 hours.
• Mucinex DM: Take 1 or 2 tablets by mouth every 12 hours. No more than 4 tablets in 24 hours.
• Mucinex DM Maximum Strength: Take 1 tablet by mouth every 12 hours. No more than 2 tablets in 24 hours.

Safe and effective use of guaifenesin and dextromethorphan is not established for children under 12 years of age.

Guaifenesin/dextromethorphan should not be used with MAO inhibitors like phenelzine (Nardil), selegiline (Zelapar, Emsam, and Eldepryl), tranylcypromine (Parnate), procarbazine (Matulane), rasagiline (Azilect) and isocarboxazid (Marplan). Such combinations increase the risk of serious side effects. Guaifenesin/dextromethorphan should not be used within 14 days of using a MAO inhibitor.

There are no adequate studies done on guaifenesin and dextromethorphan determine safe and effective use in pregnant women.

It is not known whether guaifenesin and dextromethorphan enter breast milk; therefore, it is best to be cautious before using it in nursing mothers.

What preparations of Mucinex DM are available?

Robitussin DM, Robitussin DM Maximum Strength, and Mucinex Fast-Max DM are available as oral liquid form.

• Robitussin DM contains 100 mg of guaifenesin and 10 mg of dextromethorphan in each 5 ml of liquid.
• Robitussin DM Maximum Strength and contains 400 mg of guaifenesin and 20 mg of dextromethorphan in each 10 ml of liquid.
  • Robitussin DM Maximum Strength is available in 4 fluid ounce (120 ml) and 8 fluid ounce (240 ml) bottles. Mucinex Fast-Max DM is available in 6 fluid ounce (180 ml) bottles.
  • Robitussin DM Maximum Strength is also available as liquid-filled capsules, containing 200 mg of guaifenesin and 10 mg of dextromethorphan in each capsule. Robitussin DM Maximum Strength is available in a package of 20 capsules.
• Mucinex Fast-Max DM contains 400 mg of guaifenesin and 20 mg of dextromethorphan in each 20 ml of liquid.
  • Mucinex DM and Mucinex DM Maximum Strength are available as extended-release oral tablet form.
  • Mucinex DM contains 600 mg of Guaifenesin and 30 mg of Dextromethorphan in each tablet, available as 20 tablets per package.
  • Mucinex DM Maximum Strength contains 1200 mg of Guaifenesin and 60 mg of Dextromethorphan in each tablet, available as 14 tablets per package.

How should I keep Mucinex DM stored?

Store at room temperature between 15 C and 30 C (59 F and 86 F). Do not store liquid formulations in the refrigerator.

How does Mucinex DM work?

Guaifenesin is an expectorant, which works by thinning oral mucus and increasing mucus volume. Dextromethorphan works on the cough center in the brain. It disrupts sensitivity of cough receptors and interrupts transmission of cough impulses.