Guaifenesin: Uses & Dosage

Instructor: Ian Lord

Ian has an MBA and is a real estate investor, former health professions educator, and Air Force veteran.

In this lesson, we will look at the use of guaifenesin as an expectorant as well as go over the various forms and dosages of this over-the-counter medication for adults and children.

Understanding Guaifenesin

Chris has been stuffed up with a cold for a few days now. He has asked his doctor for something to help since it hasn't gone away on its own and he still feels terrible. His doctor recommended taking guaifenesin to help him be a little more comfortable. Let's look in on what guaifenesin is used for and how it can be administered.


Guaifenesin belongs to a class of medications called expectorants. These medications thin the mucus in the air passages, which will make it easier for Chris to cough up the crud in his throat and lungs. It does not speed up recovery or treat the underlying cause of his symptoms. Guaifenesin is available as an over-the-counter medication and does not require a doctor's prescription.


Guaifenesin has a wide variety of forms and dosages. It can come in tablet, syrup, or packet forms. Regular tablets come in 200 or 400 mg doses, but extended-release versions are also available in 600 or 1200 mg doses. Syrup comes in a 100 mg per 5 ml (teaspoon) dose. Packets contain 50 or 100 mg of dissolving granules that can be put in drinks such as fruit juice.

Pregnant women should not take guaifenesin unless they have consulted with a physician. As a Category C medication, it should only be used when the benefits outweigh the risks of taking it. We currently don't know if the medication is excreted in milk, so breastfeeding mothers should also be cautious for this reason.

Chris has been instructed by his doctor that the adult dosage for guaifenesin is 100 to 400 mg every four hours. No more than 2.4 grams should be taken in total over a single day. If an extended-release version is used, the limit for adults is one or two tablets every 12 hours, but no more than four tablets or 2.4 grams in a 24-hour period. In children, the dosage limits change depending on the age of the child.

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