When you get sick and have an irritating cough, you probably just want it to go away. There are dozens of medications on the pharmacy shelves that promise to quiet the cough, but do they actually work? There are two different types of over the counter cough medications - expectorants and suppressants. They work very differently and which one you should take depends on the type of cough you are experiencing. Expectorants are a class of cough medicine that help to get mucus out of your lungs. They thin the mucus and help you cough it out more easily. Expectorants are useful when you have thick congestion and you can't cough it up on your own.