the common cold is a group of symptoms in the upper respiratory tract caused by a large number of different viruses. although more than 200 viruses can cause the common cold the perpetrator is usually the rhinovirus which is to blame for causing 10% to 40% of colds. also the coronaviruses cause about 20% of colds and the respiratory syncytial virus (rsv) causes 10% of colds.
what is a common cold?