Do not expect too much from expectorants.
There is not scientific evidence that there is any medicine that works to dry up mucus

Listen to your cough.
Is it a productive or nonproductive cough? If you have a productive cough, one where you cough up sputum, you do not really want to suppress it completely because you won’t be counting up the stuff your lungs want to rid themselves of.

Turn down your volume:
On the other hand if your cough is nonproductive that is, you are not coughing anything up, then it is good to take cough medicine designed to suppress a cough. Look for those containing the active ingredient dextromethorphan.

Smoker: Clear the Air
Plagued with chronic bronchitis may be cowed into drinking milk by the results of scientific study done by Melvyn Tockman. They found that individuals who smoked cigarettes and drank milk had a subsatantially lower frequency of chronic bronchitis than did people who smoked cigarettes but sis not drink milk . Why milk may help suppress bronchitis in smokers is still questionable.