Key takeaways
Doxylamine (Unisom SleepTabs) and Mucinex DM (guaifenesin/dextromethorphan) are both over-the-counter medications, but they have several differences. Doxylamine is an antihistamine used as a sleep aid to help you fall asleep by blocking histamine in the brain, while Mucinex DM is a combination of an expectorant (guaifenesin) and a cough suppressant (dextromethorphan) used to relieve cough and chest congestion. Doxylamine is typically taken once a day before bedtime, whereas Mucinex DM can be taken every 4 to 12 hours depending on the formulation. Doxylamine can cause next-day sleepiness and is not recommended for older adults or those with certain medical conditions, while Mucinex DM might cause stomach upset, dizziness, and drowsiness but is generally well-tolerated. Additionally, Mucinex DM has multiple formulations, including tablets, liquids, and granules, and is not recommended for children under 4 years old. Both medications should not be mixed with alcohol or other similar medications to avoid serious side effects.
