The common cold, while incurable, can make its sufferers miserable until its symptoms pass. These symptoms include nasal and chest congestion, coughing and headaches. It most cases, the cause is a viral infection for which antibiotics do not work. And while colds are extremely contagious, knowing the causes can help prevent it from spreading from one person to another.
Viruses
More than 200 viruses can cause a cold. One of the most common is the rhinovirus, according to Dr. Arthur Schoenstadt of eMedTV. It affects approximately 30 to 35 percent of adults, and is most active during early fall, spring and summer. These viruses travel in invisible droplets through the air, which others breathe in. The virus attacks the lining of both the nose and throat, causing a reaction from the immune system which produces symptoms such as a sore throat, headache and nasal congestion.
Coronavirus is another common cause, differing from rhinovirses in that only 30 strains exist. Of these 30, only three to four affect humans, and are more active during the winter and early spring.
In 30 to 50 percent of adult cold cases, the cause is not known, although the causes are assumed to be viral.
Dry Air
Dry air--whether it's inside or out-- increases the likelihood that a cold will develop as the Mayo Clinic explains. It dries the mucus membranes of the nose, thinning them. These membranes act as a barrier, preventing particles and substances from reaching the lungs. When thinning occurs due to dry air, the respiratory system becomes more susceptible to infection, according to an information website produced by Dr. Alan Greene, a San Mateo, California, pediatrician.
Smoking
People who smoke have a greater chance of developing a cold than those who do not not smoke, as KidsHealth explains. In addition, the symptoms tend to be worse, last longer and may lead to complications such as bronchitis or pneumonia.
Being Near an Infected Person
Being in close contact with a sick person increases a person's chance of developing a cold. Again, the virus-carrying droplets are in the air--once a healthy person breathes these invisible droplets in, and touches their eyes or nose, the infection begins.
Improper Handwashing
Handwashing is one of the most important steps a person can take to prevent the spread of infection, according to the Centers for Disease Control and Prevention. Each time a person coughs, sneezes or touches a tissue after blowing their nose, their next stop should be the sink with antibacterial soap.
Touching Infected Objects
Touching items such as a door knob or telephone, or sharing objects such as towels or hairbrushes, can easily infect an otherwise healthy person.
