Upper Respiratory Tract Infections

Definition and Classification

Upper respiratory tract infections (URIs) are acute infections affecting the nose, sinuses, pharynx, and larynx, and include common cold, pharyngitis, acute sinusitis, acute otitis media, and laryngitis, as defined by the American Academy of Family Physicians and the European Society of Clinical Microbiology and Infectious Diseases 1, 2
The American Academy of Family Physicians and the European Society of Clinical Microbiology and Infectious Diseases consider common cold (nasopharyngitis) as an inflammatory syndrome of the upper pharynx with varying degrees of nasal inflammation, typically viral in origin 1
Acute sinusitis (rhinosinusitis) is inflammation of the sinus cavities, often associated with the common cold, according to the American Academy of Allergy, Asthma, and Immunology and the European Society of Clinical Microbiology and Infectious Diseases 1, 3

Nasal symptoms of URIs include congestion, discharge, and postnasal drip, as described by the American College of Chest Physicians and the American Academy of Family Physicians 2, 4
Throat symptoms include throat clearing and pharyngeal discomfort, though not prominent in nonspecific URIs, according to the American Academy of Family Physicians 2, 5
Systemic symptoms of URIs include low-grade fever, headache, and malaise, as reported by the European Society of Clinical Microbiology and Infectious Diseases 1
Cough is often present but not the dominant feature, distinguishing URIs from lower respiratory infections, as noted by the American College of Chest Physicians and the American Academy of Family Physicians 2, 4

Most uncomplicated URIs resolve spontaneously within 1-2 weeks, according to the American Academy of Family Physicians 2, 5
Viral sinusitis associated with colds resolves within 21 days without antibiotics, as stated by the American Academy of Allergy, Asthma, and Immunology 3

The vast majority (>80-90%) of acute URIs are caused by viruses, including rhinoviruses, coronaviruses, parainfluenza viruses, respiratory syncytial virus, adenoviruses, and enteroviruses, as reported by the European Society of Clinical Microbiology and Infectious Diseases and the American College of Chest Physicians 1, 2, 4
Up to 90% of viral upper respiratory infections show CT evidence of sinus involvement, yet these resolve without antibiotics, according to the American Academy of Allergy, Asthma, and Immunology 3

Acute bacterial sinusitis follows only 0.5% to 13% of viral URIs, as stated by the American Academy of Allergy, Asthma, and Immunology 3
Bacterial complications such as bacterial rhinosinusitis or pneumonia are rare, according to the American Academy of Family Physicians 2, 5
Purulent nasal discharge and sputum do not predict bacterial infection, and patients with these symptoms do not benefit from antibiotics, as noted by the American Academy of Family Physicians and the European Society of Clinical Microbiology and Infectious Diseases 2, 5, 6

Symptoms of the common cold typically last up to 2 weeks, with patients advised to follow up only if symptoms worsen or exceed this expected recovery time 7
The majority of viral URIs are self-limited, with most episodes resolving within the first week 8
The typical course of acute pharyngitis is less than 1 week 8, 9
Even when caused by Group A Streptococcus, antibiotics only shorten the duration of acute pharyngitis by 1-2 days, with modest clinical benefit 9
Symptom duration of acute rhinosinusitis ranges from 1 to 33 days, with most episodes resolving within a week 8, 9
Symptoms of acute rhinosinusitis persisting beyond 10 days without improvement suggest possible bacterial superinfection rather than typical viral course 7

The American College of Physicians and CDC guidelines emphasize that understanding natural symptom duration is critical for avoiding unnecessary antibiotic use 7, 8
Symptoms lasting >10 days without improvement warrant consideration of bacterial complications 7
"Double sickening" (worsening after initial improvement at day 5-7) suggests bacterial superinfection 7
Severe symptoms (fever >39°C with purulent discharge for ≥3 consecutive days) may indicate bacterial infection requiring different management 7

Do not prescribe antibiotics based on symptom duration alone within the first 10 days, as this represents the normal viral course 7
Patients seeking care often benefit most from reassurance about expected duration and symptomatic management rather than antimicrobial therapy 7