Guaifenesin is a member of methoxybenzenes. ChEBI 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. 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. Although it is principally believed that guaifenesin elicits an action to facilitate productive cough to manage chest congestion, it is not known whether the agent can reliably mitigate coughing. Regardless, on March 1, 2007, the FDA received a petition asking the FDA to notify the public that some antitussives, expectorants, decongestants, antihistamines, and cough/cold combinations are not known to be safe and effective in children under the age of 6 years. After the negotiation between FDA and major manufacturers, a voluntary transition of labels for not using guaifenesin in children under the age of 4 years was endorsed by FDA in 2008. Furthermore, there has also been contemporary research to suggest that guaifenesin possesses and is capable of demonstrating anticonvulsant and muscle relaxant effects to some degree possibly by acting as an NMDA receptor antagonist. DrugBank Guaifenesin is an Expectorant. The physiologic effect of guaifenesin is by means of Decreased Respiratory Secretion Viscosity, and Increased Respiratory Secretions. FDA Pharm Classes View More…