When you're sick, mucus can be overwhelming. Mucinex immediate and extended-release bi-layer tablets provide fast and lasting relief for up to 12 hours, helping loosen phlegm and relieve chest congestion caused by the common cold." Directions: Do not crush, chew, or break the tablet. Take with a full glass of water. Adults and children 12 years and older: 1 tablet every 12 hours. Do not exceed 2 tablets in 24 hours. Warnings: Allergy alert: Do not use if allergic to guaifenesin. Consult a doctor if you have chronic cough, breathing difficulty, or are pregnant or breastfeeding.