Which over-the-counter medications should be taken for colds and "flu"?

Every year, millions of people use over-the-counter products to relieve the symptoms caused by the common cold or influenza (the "flu"). The common cold and flu are viral infections of the respiratory tract, which include the throat, nose, airways and lungs. Most people get colds in the winter and spring, but it is possible to get a cold at any time of the year. Differentiating between colds and the flu may be necessary when determining the most appropriate treatment option and when making a decision about whether or not referral is needed.