Geri-Tussin DM Cough and Cold Relief Temporarily relieves cough due to minor throat and bronchial irritation, which can occur when patients suffer from the common cold. Geri-Tussin DM works by helping loosen phlegm and thin bronchial secretions to bronchial drain tubes. Strength: 100 mg - 10 mg, per 5 mL. Volume: 16 oz. 1 Each.