Key takeaways
Mucinex D (guaifenesin/pseudoephedrine) and dextromethorphan (Delsym) are both over-the-counter medications, but they serve different purposes. Mucinex D is a combination of an expectorant (guaifenesin) and a decongestant (pseudoephedrine), which helps relieve stuffy nose, chest congestion, and sinus pressure. It is taken every 12 hours and is available in generic form. On the other hand, dextromethorphan is a cough suppressant that helps relieve dry cough by suppressing the cough reflex. It comes in both extended-release and immediate-release forms, with dosing intervals of 12 hours and 6-8 hours, respectively. While Mucinex D can cause trouble sleeping and headache, dextromethorphan may cause nausea and, rarely, drowsiness. Additionally, Mucinex D is not recommended for people with certain medical conditions like high blood pressure, whereas dextromethorphan should be used cautiously with other medications that raise serotonin levels. Neither medication should be taken with monoamine oxidase inhibitors (MAOIs).
