Most codeine cough medicines also have an expectorant in them as well so when you do cough it does help you get stuff out. None of the prescription cough medicines completely eliminate coughing so you'll still be able to clear mucus from your respiratory system.

I'm on one right now because I've got a pretty severe case of bronchitis, but I only ever take it at night time because even a little bit of codeine gets me hella high, and even then it only mildly reduces my cough.