During the flu season, the majority of respiratory illnesses are caused by organisms other than the flu (rhinoviruses, coronaviruses, parainfluenza, etc.). While the common cold and influenza share many clinical features, acute cold symptoms typically appear gradually over one to two days, whereas influenza symptoms (high fever, severe muscle aches, dry cough, severe headache) are typically more severe and abrupt in onset, often developing within hours.
Acute Upper Respiratory Infection (Cold) Symptoms
Symptoms in otherwise healthy individuals include:
• Sore throat and sneezing occur early in the course of the infection and usually resolve in 3 - 6 days.
• Low grade fever (less than 100 degrees Fahrenheit) and muscle aches commonly accompany these initial symptoms and usually resolve within a week.
• Nasal congestion, sinus pressure, ear pressure are common symptoms and usually persist through the first week of illness. About 30% of patients still have these symptoms at 2 weeks, although they should be improving after 7 - 10 days.
• Nasal or post-nasal drainage is usually clear and watery the first few days, but often becomes thick and discolored (green to yellow) after several days. Discolored secretions do not automatically imply that a bacterial infection is present; most improve after 5-7 days.
• Cough occurs in the majority of colds and is usually more productive than seen with the flu. Sputum varies from clear to yellow-green and usually resolves within 2-3 weeks, although a lingering dry cough can persist 4 weeks in up to 25% of infections.