The prevention and treatment of viral respiratory disorders
A briefing from the Board of Science
September 2007
What is the common cold?
The common cold (acute viral nasopharyngitis or coryza) is an illness caused by viral infection of the nasal mucous membranes, although it can affect other organs within the body, such as the sinuses, ears and lungs. There are over 100 types of virus capable of causing the common cold (these include coronavirus, respiratory syncytial virus (RSV), parainfluenza virus Types I-IV, coxsackie virus A21 and B3, echovirus Types 11 and 20, adenovirus, and other picornaviruses).[see reference 3] Rhinoviruses, however, are the most important and cause between 30 and 50 per cent of the cases.[see reference 4] Colds are usually self-limiting, meaning they do not need medical intervention, [see reference 5] although symptoms can be treated to improve comfort during infection (see the section on symptom-relief).
Symptoms of the common cold can include sneezing, runny nose, blocked nose, sore or scratchy throat, cough, hoarseness, along with general symptoms such as headache, fever, chills, and generally feeling unwell. Colds last approximately one week on average, with mild colds lasting only two or three days and severe colds lasting up to two to three weeks. It is estimated that the average adult will catch two to three colds per year, while children may catch up to a dozen or more depending on their age and exposure.[see reference 6] Research has shown that stress can lead to an increased susceptibility to the common cold and influenza.[see reference 7]
For further information about the common cold and the viruses that cause it please see Cardiff University common cold centre,[see reference 8] Medline Plus,[see reference 9] and NHS Direct Online.[see reference 10]
The common cold can be symptomatically similar to influenza, although it is typically a milder illness. It is easy to confuse influenza with a heavy cold, although influenza has symptoms that an infected individual will rarely suffer with a cold, such as a high fever, a ‘shivery’ feeling, headache, aching limbs and loss of energy.[see reference 6] The increased incidence of colds during the winter months may be attributed to the fact that more people are indoors and close to each other. In addition, many cold viruses thrive in low humidity, as this makes nasal passages drier and more vulnerable to infection.[see reference 11] For more information see the section on symptom comparison.