Dextromethorphan-Guaifenesin Uses

The combination of dextromethorphan and guaifenesin is used to loosen mucus (phlegm) and make it easier to clear from the air passages. It is also used to provide temporary relief from cough due to respiratory infections such as the common cold and flu and cough due to inhaled irritants. This medication can help to lessen the intensity of coughing and suppress the cough impulse to allow you to get some rest at night.

There may be other uses of dextromethorphan-guaifenesin—your pharmacist or doctor can give you further drug information.

Dextromethorphan-Guaifenesin Mechanism of Action

Dextromethorphan acts on the area of the brain responsible for coughing and suppresses the cough reflex. Guaifenesin thins the mucus and makes it easier to clear from the respiratory passages.

Dextromethorphan-Guaifenesin Doses

Typical doses of dextromethorphan and guaifenesin are as follows: 

In adults and children 12 years of age and above:

• Extended-release tablets (for example, Mucinex DM): These tablets contain 30 mg dextromethorphan and 600 mg guaifenesin. The dose is 1-2 tablets twice a day as needed. The maximum dose is 4 tablets per day.
• Syrup (for example, Diabetic Tussin DM, Robitussin DM Max): 10-20 mL (2-4 teaspoons) every 4 hours as needed with a maximum of 6 doses per day.

In children 6-12 years of age:

• Syrup (for example, Children’s Mucinex Cough): 5-10 mL (1-2 teaspoons) every 4 hours as needed with a maximum of 6 doses per day.

In children 4-6 years of age:

• Syrup (for example, Children’s Mucinex Cough): 2.5-5 mL (1/2-1 teaspoon) every 4 hours as needed with a maximum of 6 doses per day.

Note: It’s important to read the package label carefully because manufacturers use slightly different strengths of the two active ingredients in each product, and the dosages can vary.