Mucinex Maximum Strength Fast Max Severe Congestion and Cough 20 Caplets When cough and chest congestion strike, reach for Maximum Strength Mucinex Fast-Max Severe Congestion & Cough caplets. These fast release caplets contain effective active ingredients to provide powerful relief from cough and cold symptoms. Dextromethorphan HBr, a cough suppressant, reduces the urge to cough. Guaifenesin, an expectorant, targets bothersome chest congestion by thinning and loosening mucus, providing bothersome mucus relief. Count on Mucinex for powerful relief from your worst cough & cold symptoms. Use as directed. For ages 12 years and older.