What is ACC 200? ACC 200 is an over-the-counter (OTC) medication available at any Dis-Chem Pharmacy. It comes in an effervescent tablet form and dissolves in water to break down or disrupt mucus. How does ACC 200 work? The active ingredient N-acetylcysteine (NAC) acts on thick and sticky mucus in the respiratory airways, breaking down the bonds that hold it together. It does not significantly increase the quantity of mucus or fluid in the airways and only thins it. Clearing the mucus also helps to prevent the development of infections there.