What is better at night - cough suppressant or expectorant?

Cough is useful: Those products have colorants, flavors, antihistamines and a lot of other stuff that doesn't help you recover. Why use it? Cough helps get the mucus out and is designed to clear your respiratory system. Don't suppress it.

Depends...: The cough etiology needs to be diagnosed so that it can be treated. Neither an expectorant nor suppressant treats the underlying etiology and both can be harmful in certain situations. So, you need to be evaluated by your doctor to determine the etiology of your cough and to render appropriate therapy. If you smoke, you need to quit to decrease airway inflammation, a contributing factor.