The common cold is caused by a virus, and there are more than 200 viruses which cause colds. The most widely spread are the rhinoviruses, which are the cause of nearly half of all infections.  They affect the respiratory tract, and the infection starts from the nose, then spreads to the ears and the bronchi.  Once viruses enter our bodies through the nose they penetrate the cells and multiply.

The symptoms of the common cold are numerous and the most common are: sneezing, blocked sinuses, sore throat, coughing, headache, fever, chills and general malaise.

The duration of the common cold  lasts from two days to one week, but more severe cases may last up to two weeks.

Generally, this disease has no serious complications, at most it may develop into sinusitis, especially when the cold lasts for more than 10 days without improving or getting worse. But sinusitis only occurs in 1-5% of cases.

The common cold is an extremely contagious illness which is spread through the air and through contact. Viruses are spread in the air through sneezing and coughing, and are transferred from one person to another through direct contact of hands, and by touching the eyes and face. Just the smallest quantity of a cold virus is sufficient to spread the infection.

The common cold is extremely frequent in children whose immune defence mechanisms are less developed than in adults. But colds are also frequent in the aged and in debilitated and stressed people.