health

The common cold is caused by at least 200 viruses that had been identified
as of 2008. A cold virus typically enters the body through the nasal
passages or mouth, but can also enter through the mucous membranes
covering the eyes. The virus spreads to the tissues lining the area between
the nose and the back of the throat, where it rapidly multiplies. Within
hours or a day or two after the virus enters the body, the infected person
feels a scratchy sensation at the back of the throat, followed by sneezing
and a constant flow of runny mucus from the nose. Researchers think
that these symptoms are caused by the body’s immune response to the
virus rather than by tissue damage caused by the virus.

In addition to the runny nose, sneezing, and coughing associated
with the common cold, people may also have:

• Low-grade fever (101°F [38.8°C] or lower)
  
• Muscle aches
  
• Headache
  
• Loss of the senses of taste and smell
• Loss of appetite
  
• Sore throat

Children are often sicker than adults when they get a cold because
their immune systems are less developed. Children may run a fever as
high as 102°F (38.9°C) with a cold; they may also develop an ear or sinus
infection following a cold. Children with asthma may have an attack triggered
by a cold.