Maximum Strength Mucinex DM Extended-release Bi-layer tablets provide powerful symptom relief. The product controls cough, relieves chest congestion, thins and loosens mucus and lasts for 12 hours. It contains a unique bi-layer tablet - one layer for immediate release and one layer for extended release, so the medicine starts to release right away and lasts for up to 12 hours, so you can say goodbye to retaking medicine every 4 hours. Mucinex is the #1 Cough & Cold Brand Doctors Trust* and the #1 Pharmacist Recommended Brand† as well. This product contains 42 tablets. It can be used by Adults and Children 12 years of age and over.