What a Common Cold Is
A common cold is an illness caused by a virus infection located in the nose. (1) Colds also involve the sinuses, ears, and bronchial tubes.
The symptoms of a common cold include sneezing, runny nose, nasal obstruction, sore or scratchy throat, cough, hoarseness, and mild general symptoms like headache, feverishness, chilliness, and not feeling well in general. (1, 2)
A cold is a milder illness than influenza. Influenza typically causes fever, muscle aches, and a more severe cough. However, mild cases of influenza are similar to colds. (3)
Adults average 2 to 3 colds per year and children 6 to 10, depending on their age and exposure. Children's noses are the major source of cold viruses. (4)
There are over 100 different cold viruses. Rhinoviruses are the most important and cause at least one-half of colds. (5)
Cold viruses can only multiply when they are inside of living cells. When on an environmental surface, cold viruses cannot multiply. However, they are still infectious if they are transported from an environmental site into the nose. (6, 7)
Cold viruses live only in the noses of humans and not in animals except chimpanzees and other higher primates. (4)