Cold is the most frequent infectious disease in humans with the average adult getting two to three colds a year and the average child getting between six and twelve. No cure for the common cold exists, but the symptoms can be treated. The common cold is a viral infectious disease of the upper respiratory tract which primarily affects the nose.

Signs and symptoms include coughing, sore throat, runny nose, sneezing, and fever which usually resolve in seven to ten days, with some symptoms lasting up to three weeks. Well over 200 virus strains are implicated in the cause of the common cold, the rhinoviruses are the most common.

A cold usually begins with fatigue, a feeling of being chilled, sneezing, and a headache, followed in a couple of days by a runny nose and cough. Symptoms may begin within 16 hours of exposure and typically peak two to four days after onset. They usually resolve in seven to ten days but some can last for up to three weeks. The average duration of cough is 18 days and in some cases people develop a post-viral cough which can linger after the infection is gone. In children, the cough lasts for more than ten days in 35–40% of the cases and continues for more than 25 days in 10%. Rates of symptomatic infections increase in the elderly due to declining immunity.