No one escapes the common cold. It's the leading cause of doctor visits and missed days from school and work in the United States, according to the National Institute of Allergies and Infectious Diseases. Children's noses are the major source of cold viruses.

The common cold is a viral infection of the upper respiratory tract that mostly affects the nose but can cause symptoms in the throat and sinuses. Cold symptoms are mainly due to the body's response to the infection. When a cold virus infects a nasal cell, the body responds by activating parts of the immune system and some nervous system reflexes. Symptoms vary but typically include sneezing, coughing, and a soar, scratchy throat. It is one of the most common illnesses in the world. Children have about six to ten colds a year (depending on their age and exposure); adults average two to three colds a year.

Unfortunately there is no cure for the common cold but frequent hand washing and steering clear of sick children and adults can minimize your risk of coming down with one. People are most contagious for the first two to three days of a cold; colds are not contagious after the first week.

The good news is that most colds don't last long—between 7 and 10 days—and if you feel lousy you can treat the symptoms with over-the-counter cold remedies, hot tea, extra rest, and a little TLC. Cold season runs from September until March or April. Here's a look at colds by the numbers:

  • 62 million: Number of cases of the common cold that occur each year.
  • 20 million: Number of school days missed annually due to the common cold according to the National Center for heath Statistics.
  • 22 million: Number of work days lost annually due to the common cold.
  • 100: Number of different viruses that can cause the common cold. Rhinoviruses are the most prevalent and cause at least one-half of colds.
  • 1 to 30: Number of virus particles sufficient to produce infection.
  • 8 to 12: Number of hours it takes from the time a cold virus enters the nose for it to complete the viral reproductive cycle and for a new cold virus to be released in nasal secretions.
  • 36 to 72: Number of hours it takes from the beginning of the infection to the peak of symptoms.
  • 7: Number of days an average cold lasts; mild colds last only 2 or 3 days while severe colds can last up to 2 weeks.
  • 20: Number of seconds needed for proper hand washing. No timer handy? Hum the tune, "Happy Birthday" as you rub your hands together with warm, soapy water.
  • 25 percent: Number of people who acquire cold viruses but do not develop symptoms.


The National Institute of Allergies and Infectious Diseases

The Centers for Disease Control and Prevention in association with "It's a Snap" (proper hand washing technique)

National Institutes of Health

Understanding Colds: The Nose - Side View