What is the best medicine for cough with swine flu?

It would be good to pick the ones that help expectoration as well as cough, since lung secretions that are not coughed up are part of the problem in development of secondary pneumonia from the flu, which can be a life-threatening complication. My personal choice for the best of the cough/expectorant OTC medicine would be any cough preparations that contain Guaifenesin as the primary active ingredient. This is made from a natural product with centuries, if not longer, of safe and effective use for this purpose, and it loosens congestion and sputum better than other choices for me to help clear my lungs and airway.

Guaifenesin is available OTC in generic and store brand cough medicines at very reasonable prices, and in brand name OTC cough and expectorant treatments, such as Robitussin and Mucinex. I usually prefer to use cough medicines that do not also contain decongestants, because they are not needed every time you need an expectorant or cough medicine and can be taken separately when they are really needed. Consult your pharmacist for choosing OTC medicines that can be taken safely together.

See the related questions in the related question section for this Q&A for a more comprehensive answer on how cold and flu are treated.