US National Library of Medicine
Medline Plus: Dextromethorphan
At this site read about dextromethorphan, an ingredient in many over-the-counter cough suppressants, or antitussives. This website provides brief responses to several queries about dextromethorphan including, "Why is this medication...
US National Library of Medicine
Medline Plus: Guaifenesin
This website provides responses to several questions about the expectorant medication, guaifenesin, which is found in cough medicines like Robitussin.