Expectorants are used to treat cough with phlegm (productive cough). They help the body get rid of excess phlegm by making it thinner and more liquid. Mucosolvan®, the worldwide leading cough remedy, is an expectorant.
Suppressants are used to treat dry coughs. Suppressants, also known as antitussives, reduce the body's urge to cough. It is very important to avoid taking a suppressant if there is excessive phlegm in the airways: always check with your medical expert before using a suppressant with a productive cough.
Usually it is not advisable to combine a cough suppressant and an expectorant. The expectorant will make the phlegm looser, but the suppressant will reduce the body's natural cough response, making it much more difficult to clear the airways. However, it may be useful to take an expectorant during the day and a suppressant at night, to help get an undisturbed sleep.