What causes colds and the flu?
Viruses cause colds and the flu. More than 200 different viruses can cause colds. Not as many viruses cause the flu. That's why there's a shot available for the flu and not for colds.
Bibliography
See a list of resources used in the development of this information.
Written by familydoctor.org editorial staff
Reviewed/Updated: 11/10
Created: 01/96