Mucinex DM (guaifenesin/dextromethorphan) and Dayquil Cold and Flu (acetaminophen/dextromethorphan/phenylephrine) are both over-the-counter medications used to treat symptoms of the common cold, but they have different active ingredients and uses. Mucinex DM combines guaifenesin, an expectorant that loosens mucus, and dextromethorphan, a cough suppressant. It is available in various forms, including tablets, liquids, and granules, and is typically taken every 4 to 12 hours depending on the formulation. Dayquil Cold and Flu, on the other hand, includes acetaminophen for pain and fever relief, dextromethorphan for cough suppression, and phenylephrine as a decongestant. It is available as pills and liquid, usually taken every 4 hours. While Mucinex DM focuses on relieving cough and chest congestion, Dayquil Cold and Flu addresses a broader range of symptoms, including headache, sore throat, and nasal congestion. Additionally, Dayquil Cold and Flu contains acetaminophen, which can pose a risk of liver damage if taken in excess or with alcohol, a concern not associated with Mucinex DM. Both medications should not be taken with other products containing similar ingredients to avoid overdose.