Common cold – facts & fiction


Common cold affects adults 2 to 5 times per year and children are affected even more often. The illness is characterized by a runny nose, sore throat, cough, mild fever and aches (head, muscles or joints). Common cold is caused by over two hundred different viruses. They all cause more or less the same cold symptoms, some milder others a bit more aggressive, but rarely as heavy as the influenza viruses. The rhinoviruses are responsible for 30-50 % of the cases among adults and normally cause symptoms for only 4-7 days.

Does freezing cause common cold?
A study at the Common Cold Centre in Cardiff from 2005, showed that freezing may increase the risk of getting sick, but only if you are exposed to a virus. The researchers suggest that in an environment where common cold viruses are circulating, people can be carriers of the virus without getting sick themselves. Cooling of the feet or hands causes contraction of blood vessels in the nose and throat, which inhibit the local immune system in the upper airways. This in turn makes the virus replicate and flourish – and the infection is established.

Is common cold more common in winter than summer?
The spread of virus infections like the common cold and influenza are varying during the year and the reason for this is not altogether clear. In cold seasons people tend to spend more time indoors and close together, sometimes in poorly ventilated rooms…Furthermore, in cold weather, despite warm clothing, our nose and throat are still exposed to freezing temperatures and could make us more susceptible to airway infections. If this theory is correct, covering of the nose and mouth in cold weather may prevent common cold. The common cold viruses also circulate during summer time, but the risk of getting the virus is generally lower in summer than winter. The chance of getting the cold is directly linked to hours of exposure to the virus.

Does stress and air travel increase the risk of common cold?
Stress is associated with down regulating of the immune systems general resistance against infections. Not surprisingly, research has shown that psychological and certain environmental stress increases our risk for certain viral infections. This is also shown for common cold viruses in people with high levels of emotional stress. Also, being onboard an airplane increases the risk of being infected, most likely because of the close contact (proximity) between travelers and the ventilation systems of airplanes is ideal for transmission of airborne disease. Long overseas flights are more risky than short domestic flights.

Why are we feeling tired and lacking appetite during cold or the flu?
Symptoms like fever, headache, muscular pain, fatigue and reduced appetite are caused by chemical components (cytokines) produced by the white blood cells fighting the infection. This is the body’s way of telling us to rest and be cautious of how we use our energy while fighting the infection. Heavy cold or flu will increase the amount of cytokines and therefore increase the fever and fatigue.

How are common colds transmitted?
Virus particles in droplets produced during coughing, sneezing and via fingers being in contact with mouth, nose and eyes, are the main route of transmission. Our hands can spread or pick up the virus when in contact with objects in our environment that we touch regularly, such as door handles, light switches and utensils in the canteen. By the way, kissing on the cheek or hugging people are most likely not the common ways to spread a virus, although if the person is infected then the risk is increased.

Will there be a cure for common cold?
It is unlikely that we will find a cure or a vaccine because the common colds are caused by so many different viruses. Moreover, the virus often changes its “appearance” to make it even harder for both our immune system and our scientists us to find a permanent solution to the most common health problem in the world.

How to reduce the risk of catching a common cold?

  • Use a paper handkerchief over your mouth and nose to protect others when you cough or sneeze. Throw the handkerchief away after use. Then wash your hands.
  • Cough or sneeze into your elbow if you do not have a paper handkerchief available.
  • Wash hands frequently and thoroughly, especially after you have been out in public.
  • Hand disinfection with an alcohol hand rub is an option when hand washing is not possible, for example when traveling.
  • Avoid touching your nose and mouth as much as you can and especially after shaking hands with people
  • Keep a safe distance (1m) to people that are sneezing or coughing