Respiratory syncytial virus (RSV) -- responsible for 10% of colds
Rhinoviruses and the Common Cold
Rhinoviruses, the worst offenders, are most active in early fall, spring, and summer. More than 110 distinct rhinovirus types have been identified. Most rhinoviruses seldom produce serious illnesses. However, other cold viruses, such as parainfluenza and RSV, can lead to severe lower respiratory infections, such as pneumonia, in young children.
Coronaviruses and the Common Cold
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.
Other Causes of the Common Cold
About 10% to 15% of adult colds are caused by viruses also responsible for other, more severe respiratory illnesses.
The causes of 20%-30% 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.
National institute of Allergy and Infectious Diseases: "Common Cold."
Mayo Clinic: "Common Cold."
Canadian Center for Occupational Health and Safety: "Common Cold."
University of Virginia Health System: "Upper Respiratory Infection (URI or Common Cold)."