Cold Facts

Common Cold

Overview

Sneezing, scratchy throat, runny nose—everyone knows the first signs of a
cold, probably the most common illness known. Although the common cold is
usually mild, with symptoms lasting 1 to 2 weeks, it is a leading cause of
doctor visits and missed days from school and work. According to the Centers for
Disease Control and Prevention, 22 million school days are lost annually in the
United States due to the common cold.

In the course of a year, people in the United States suffer 1 billion colds,
according to some estimates.

Children have about 6 to 10 colds a year. One important reason why colds are
so common in children is because they are often in close contact with each other
in daycare centers and schools. In families with children in school, the number
of colds per child can be as high as 12 a year. Adults average about 2 to 4
colds a year, although the range varies widely. Women, especially those aged 20
to 30 years, have more colds than men, possibly because of their closer contact
with children. On average, people older than 60 have fewer than one cold a
year.

In the United States, most colds occur during the fall and winter. Beginning
in late August or early September, the rate of colds increases slowly for a few
weeks and remains high until March or April, when it declines. The seasonal
variation may relate to the opening of schools and to cold weather, which prompt
people to spend more time indoors and increase the chances that viruses will
spread to you from someone else.

Seasonal changes in relative humidity also may affect the prevalence of
colds. The most common cold-causing viruses survive better when humidity is
low—the colder months of the year. Cold weather also may make the inside lining
of your nose drier and more vulnerable to viral infection.