Muco-fen DM is an extended release formula of two drugs,
Dextromethorphan and
guaifenesin, which are both common ingredients in many OTC cough syrups and gelcaps. Dextromethorphan is a decongestant, and guaifenesin an expectorant. Both have been known to cause drowsyness, and DXM can be quite disassociative at high doses. In combo, drowsiness and groggyness are listated as possible side affects for this drug, and I know many people who are sensitive to it and only take it at night. More info at
http://guaifenesin.and.dextromethorphan.drugs.com/
and
http://www.qvar.com/pdf/Muco_Fen_DM.pdf
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