A common cold is a nonspecific, acute, self-limited infection of the upper respiratory tract. It more commonly occurs in children and most infections occur during fall and winter. Common cold is a viral infection of the upper respiratory tract, causing rhinorrhea, nasal obstruction, and coughing. Diagnosis is usually clinical and treatment is mostly symptomatic. The most important complication of common cold is secondary bacterial infection (e.g., pneumonia).
- Leading cause of ambulatory care visits in the US 
- More common in children 
- Seasonal pattern: Most infections occur during the fall and winter.
Epidemiological data refers to the US, unless otherwise specified.
Infection of the nasal epithelium triggers the inflammatory response, which leads to: 
Main symptoms: rhinorrhea, nasal obstruction, sneezing, and coughing 
- Symptoms typically resolve after 1 week.
- Cough may persist for 3 weeks.
- Other symptoms: sore throat, hoarseness, fever (uncommon), malaise, and fatigue
- Physical examination finding
- Extension of the viral infection to surrounding structures (e.g., ear, sinuses, larynx)
- Secondary bacterial infection, i.e., pneumonia (mostly due to S. pneumoniae, H. influenzae, M. catarrhalis, S. aureus)
- Exacerbation of asthma and/or chronic bronchitis
We list the most important complications. The selection is not exhaustive.