Cause of the Common Cold

Ever wonder what causes a common cold? The answer is overwhelming, as more than 200 different viruses are known to cause the miserable signs and symptoms of the common cold.

The most common causes of the common cold are viruses -- rhinoviruses, coronaviruses, and the respiratory syncytial virus (RSV). The rhinovirus group causes 10% to 40% of colds. The coronaviruses and RSV are responsible for 20% and 10% of cases, respectively.

Common Cold Causes: Rhinoviruses

Rhinoviruses, the worst offenders, are most active in early fall, spring, and summer. More than 110 distinct rhinovirus types have been identified. These viruses grow best at temperatures of about 91 degrees, that perfect body temperature right inside the human nose. Most rhinoviruses seldom produce serious illnesses. Other cold viruses, such as parainfluenza and respiratory syncytial virus, produce mild infections in adults but can lead to severe lower respiratory infections, such as pneumonia, in young children.

Common Cold Causes: Coronaviruses

Scientists think coronaviruses cause a large percentage of adult colds. These cold viruses are most active in the winter and early spring. Of the more than 30 kinds of coronaviruses, three or four infect humans. The importance of coronaviruses as a cause of colds is hard to assess because, unlike rhinoviruses, they are difficult to grow in the laboratory.

Other Causes of the Common Cold

About 10 to 15 percent of adult colds are caused by viruses also responsible for other, more severe respiratory illnesses.

The causes of 30 to 50 percent of adult colds, presumed to be viral, remain unidentified. The same viruses that produce colds in adults appear to cause colds in children. The relative importance of various viruses in children's colds, however, is unclear because it’s difficult to isolate the precise cause of symptoms in studies of children with colds.

There is no evidence that you can get a cold from exposure to cold weather or from getting chilled or overheated.

Stress, Allergies, and the Common Cold

There is also no evidence that your chances of getting a cold are related to factors such as exercise, diet, or enlarged tonsils or adenoids. On the other hand, research suggests that psychological stress and allergic diseases affecting your nose or throat may have an impact on your chances of getting infected by cold viruses.