Mucinex 600mg is an expectorant medication containing guaifenesin in extended-release bi-layer tablets. This 20-tablet pack provides 12-hour relief from chest congestion by thinning and loosening mucus, featuring both immediate and extended-release properties. The active ingredient guaifenesin works as an expectorant to help relieve chest congestion by making coughs more productive. The bi-layer tablet technology provides both quick symptom relief and extended 12-hour duration. The 600mg strength is formulated to help break up mucus and thin bronchial secretions to help clear congestion.