Coughs send more people to the doctor's office than any other specific symptom. And Americans spend billions of dollars every year on over-the-counter medications like suppressants and expectorants to treat them.

Clearly we're concerned about our coughs. Clearly lots of us rely on medications to treat them. What's unclear is the answer to this core question: Do these medicines work?

"We've never had good evidence that cough suppressants and expectorants help with cough," says Norman Edelman, MD, senior scientific advisor at the American Lung Association. "But people are desperate to get some relief. They're so convinced that they should work that they buy them anyway."

Should you use these products? Here's what you need to know about the pros and cons of common cough medicines.