I just went to the doctor for a really bad cough. I told him I have been using Robitussin. He told me to switch to Mucinex DM because it has more of one of the important ingrediants than robitussin (he told me which one, I just don't remember which it was). I have to take it with food and water, otherwise, it will make me sick to my stomach. It seemed to have worked at clearing out my nose.