Are you trying to find a trustworthy adult remedy for chest congestion? For excessive mucus relief, go no further than our Maximum Strength Mucinex 12 Hour Expectorant. This excellent expectorant, which contains a strong 600 mg of guaifenesin, thins and loosens mucus, increasing the effectiveness of coughing. You may rely on Mucinex to provide effective relief from chest congestion when the cold and flu season arrives. Our first bi-layer tablet lasts up to 12 hours and offers both instant and extended-release.