Mucinex is a widely-available over the counter product used to clear chest congestion and break up mucus in airways. It is available in multiple forms and strength levels, notably tablets and liquids. The exact dosage and strength of Mucinex Tablets may vary, as it is provided in different packs containing 10 or 20 tablets, each with 400-1200mg of its active ingredient, guaifenesin. When taking Mucinex, be sure to read the label and instructions carefully and consult with a healthcare professional if any questions arise.