Key takeaways
Mucinex DM (guaifenesin / dextromethorphan) and Delsym (dextromethorphan) are both over-the-counter medications used to relieve coughs caused by minor throat or lung irritation, such as the common cold. They both contain dextromethorphan, which is an antitussive or cough suppressant. However, Mucinex DM also includes guaifenesin, an expectorant that helps loosen mucus in the airways, making it easier to cough out. Mucinex DM is available in various forms, including tablets, oral liquids, and dissolvable granules, while Delsym is available as an extended-release syrup and immediate-release caplets. Mucinex DM is typically taken every 4 to 12 hours depending on the formulation, whereas Delsym is taken every 6 to 12 hours. Both medications can cause drowsiness, but Mucinex DM may also cause dizziness and stomach upset. You should avoid taking either medication with monoamine oxidase inhibitors (MAOIs) due to the risk of serotonin syndrome. Additionally, Mucinex DM should not be taken with other products containing dextromethorphan to prevent overdose.
