Key takeaways
Doxylamine (Unisom SleepTabs) and guaifenesin extended-release (ER) (Mucinex ER) are both over-the-counter medications, but they have several differences. Doxylamine is an antihistamine used to help you fall asleep by blocking histamine in the brain, while guaifenesin ER is an expectorant that helps loosen mucus in your airways to relieve chest congestion. Doxylamine is typically taken once a day before bedtime, whereas guaifenesin ER is taken every 12 hours as needed. Doxylamine can cause next-day sleepiness and is not recommended for older adults or those with certain medical conditions, while guaifenesin ER is generally well-tolerated with few side effects. Additionally, doxylamine is not safe to combine with alcohol or other antihistamines, whereas guaifenesin ER does not have known interactions with alcohol but should not be taken with other similar medications to avoid overdose. Both medications are available in generic forms, making them more affordable options.
