Fig. 1.

Common cold symptoms and possible complications result from a dynamic interplay between infecting virus characteristics and host’s immune response. In the majority of cases, common cold is a relatively mild and self limited illness. However, affected individuals with defective immunity -either because of an underlying condition (i.e. asthma, immunodeficiency, young or old age) or as a result of environmental conditions (i.e. smoking, stress, pollution)- may experience severe (even fatal) complications.