Maximum Strength. 12 Hour. Controls Cough. Thins and Loosens Mucus. 1200 mg Guaifenesin & 60 mg Dextromethorphan HBr. Helps loosen phlegm (mucus) and thin bronchial secretions to rid the bronchial passageways of bothersome mucus and make coughs more productive. Temporarily relieves: cough due to minor throat and bronchial irritation as may occur with the common cold or inhaled irritants; the intensity of coughing; the impulse to cough to help you get to sleep.