Guaifenesin is the only expectorant approved by the Food and Drug Administration (FDA). The exact way Mucinex works is unclear. However, it has several significant effects, including the following ...

If you have a bottle of Mucinex in your medicine cabinet ... reducer), dextromethorphan (cough suppressant), guaifenesin (expectorant), phenylephrine (decongestant), and diphenhydramine ...

Dextromethorphan HBr 5mg, guaifenesin 100mg; per packet; orange creme flavor; contains (phenylalanine 2mg, magnesium 6mg, sodium 2mg) per packet. Empty entire contents of packet onto tongue and ...