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Causes of colds
Last reviewed: 06.07.2025
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The causes of colds are simple. On average, adults get 4 to 6 colds a year, and children get 6 to 8. Colds account for 40% of all time lost from work and 30% of all school absences. There are millions of colds in the United States each year. [ 1 ] What causes colds and how can you avoid them?
How does a cold start?
A cold starts with droplets that are spread through the air when sneezing and coughing or from heavily soiled fingers. The virus then moves deep into the nasal passages, where it attaches to the adenoid area and begins to multiply. Within 10 to 12 hours, the body tries to protect itself by clogging the glands with mucous secretions, and the person begins to sneeze and cough. That's when you feel the first signs of a cold.
Typically, cold symptoms get worse during the first 48 hours, then begin to subside. Most colds last about a week, although a severe cold can last longer.
Viruses that cause colds
More than 200 different viruses cause the common cold. The most common ones include:
- Rhinoviruses - cause 10% to 40% of colds
- Coronaviruses - cause 20% of colds
- Respiratory syncytial virus (RSV) - responsible for 10% of colds
Rhinoviruses as causes of colds
Rhinoviruses are nasty offenders that are most active in early fall, spring, and summer. More than 110 different types of rhinoviruses have been identified. The most dangerous rhinoviruses often cause serious illness. For example, some viruses that cause the common cold or parainfluenza can cause a serious lower respiratory infection, pneumonia, especially in young children. [ 2 ]
Coronaviruses as causes of colds
Scientists believe that coronavirus causes the largest percentage of colds in adults. These cold viruses are most active in winter and early spring. Of the more than 30 types of coronaviruses, three or four actively infect people.
[ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ]
Other causes of colds
About 10% to 15% of adults are infected with cold viruses, which can also cause other, more serious upper respiratory illnesses.
The cause of 20% to 30% of colds in adults that are thought to be viral still remains unidentified. Doctors say that the viruses that cause colds in adults are likely to cause colds in children, too. But in reality, when examining children with colds, it is quite difficult to determine the exact cause of their symptoms.
There is still no evidence that colds are caused by hypothermia or overheating of the body.
Stress, allergies and colds
There is no evidence that colds are caused by factors such as excessive exercise, excessive dieting, or enlarged tonsils or adenoids. On the other hand, research shows that psychological stress and allergies affecting the sinuses or lining of the throat may increase the risk of infection from cold viruses.
The causes of colds can be prevented by taking protective measures. For example, avoiding contact with people infected with viruses, protecting yourself from stress, and be sure to include vegetables and fruits in your diet.