The common cold refers to a viral infection of the upper respiratory tract. This infection can be due to different types of viruses, so there is no one "cold virus." In fact, over 200 types of viruses are known to cause the common cold. Characteristic symptoms include
The following symptoms and signs may also occur:
Symptoms of a cold usually last from four to 14 days.
Other conditions, including allergies and the flu, can cause symptoms similar to those of the common cold. While flu symptoms are generally more severe, it is often difficult to tell the difference between a cold and the flu. Other conditions, like bacterial strep throat or sinus infections, may mimic symptoms of a cold.