A medication used to eliminate phlegm and treat chest congestions.


An expectorant commonly found in OTC products for the symptomatic relief from congested chests and coughs associated with cold, bronchitis, and/or other breathing illnesses.


Guaifenesin possesses a storied history, having been originally formally approved by the US FDA in 1952 and continues to be one of very few - if not perhaps the only drug that is readily available and used as an expectorant [11]. Since that time the agent has been a combination component of various prescription and non-prescription over-the-counter cough and cold products and is currently a widely available over-the-counter generic medication [11]. Although it is principally believed that guaifenesin elicits an action to facilitate productive cough to manage chest congestion [4, 7, 9, Read more



Guaifenesin is an expectorant that is indicated for providing temporary symptomatic relief from congested chests and coughs which may be due to a cold, bronchitis, and/or other breathing illnesses [FDA Label, Read more


Guaifenesin is categorized as an expectorant that acts by enhancing the output of phlegm (sputum) and bronchial secretions via decreasing the adhesiveness and surface tension of such material [ Read more

Mechanism of action

Although the exact mechanism of action of guaifenesin may not yet be formally or totally elucidated, it is believed that expectorants like guaifenesin function by increasing mucus secretion [ Read more


Studies have shown that guaifenesin is well absorbed from and along the gastrointestinal tract after oral administration [ Read more

Protein binding

Information regarding the protein binding of guaifenesin is not readily available or accessible.

Volume of distribution

The geometric mean apparent volume of distribution of guaifenesin determined in healthy adult subjects is 116L (CV=45.7%) [ Read more


The mean clearance recorded for guaifenesin is about 94.8 L/hr (CV=51.4%) [11].

Half life

The half-life in plasma observed for guaifenesin is approximately one hour [ Read more

Route of elimination

After administration, guaifenesin is metabolized and then largely excreted in the urine [ Read more


The most prevalent signs and symptoms associated with an overdose of guaifenesin have been nausea and vomiting [7].

Although adequate and well-controlled studie... Read more

Adverse Effects

Effect Regions Age Groups Incidences Evidence Type
Vomiting US
Varying Reports
Nausea US
Varying Reports


  • Hypersensitivity:
    • true
  • Sex Group: all
  • Regions: US

Food Interactions

Take with a full glass of water.

Take with or without food. The absorption is unaffected by food.