Why am I still coughing if I have taken tussionex?

Gag reflex. Tussionex is a very strong cough medication so when one continues to cough despite taking this medication, it is usually a gag reflex cough. This type of cough is a protective mechanism (when fluids "go down the wrong pipe, " you want to cough). Instead of trying to stop this cough, it would be better to keep the mucous thin so that it comes up easier. This is done with an expectorant (mucinex.).