Colds - Adults have an average of two to four colds a year, while young children have six to eight. Colds are the leading cause of doctor visits in the United States. However, a doctor's visit is unnecessary for most healthy people, unless the cold exceeds 10 to 14 days, when a secondary infection must be ruled out. A cold can also trigger asthma or bronchitis.⁶⁵

Flu - Flu is seasonal, and occurs from October through mid May.⁶⁶ Influenza kills between 20,000 and 40,000 Americans annually, and over 300,000 people are hospitalized.

Symptoms

Colds - Colds may start gradually as a scratchy or sore throat, or increasing congestion in the nose.⁶⁸ Other symptoms include a runny nose, sneezing, cough and in some cases slight fever.⁶⁹

Flu - Influenza begins abruptly, and symptoms often are more severe than cold symptoms. They include headache, chills, a dry cough, sore throat, rapidly rising fever, general malaise, and muscle and joint pain.⁷⁰