The common cold, or coryza, caused mainly by rhinoviruses.They generally transmit via aerosols of respiratory droplets or indirect contact with the infected. Primary site of infection is nose and respiratory tract. These viruses infect the upper respiratory tract but not the lungs. The symptoms are congestion nasal discharge, sore throat, hoarseness, cough, headache, tiredness which usually last from 3 to 7 days.