Guaifenesin is used to control cough and is sometimes combined with dextromethorphan, an antitussive, such as in Mucinex DM or Robitussin DM [REF].
A 2008 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 whether it is effective or not [REF].