Guaifenesin is an expectorant drug sold over the counter and usually taken orally to assist the bringing up (expectoration) of phlegm from the airways in acute respiratory tract infections. Guaifenesin is sold as pills or syrups under many brand names. Single-ingredient formulations of guaifenesin are available, and it is also included in many other over-the-counter cough and cold remedy combinations. The principal use of guaifenesin is in the treatment of coughing. A Cochrane Collaboration meta-analysis of over-the-counter medicines for acute cough in children and adults concluded that there was not enough high-quality clinical data to prove or disprove the effectiveness of any examined drug including guaifenesin. Guaifenesin is thought to act as an expectorant by increasing the volume and reducing the viscosity of secretions in the trachea and bronchi.
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