Upper Respiratory Tract Infection

Upper respiratory tract infection is a broad term for infection of the nasal passages, pharynx, larynx and associated structures. It is predominantly viral in aetiology, among the commonest reasons for presentation to primary care, and a major driver of inappropriate antibiotic prescribing. The clinical task is distinguishing self limiting viral illness from the minority of presentations requiring specific intervention.

Aetiology

Rhinovirus is the commonest single cause, alongside coronaviruses, influenza, parainfluenza, respiratory syncytial virus and adenovirus. There is considerable overlap between the specific syndromes (common cold, sinusitis, pharyngitis, laryngitis), since these represent points along a spectrum of the same underlying viral respiratory infection rather than entirely distinct conditions in most cases.

Bacterial infection accounts for a minority of presentations, either as a primary cause (group A streptococcal pharyngitis) or as secondary bacterial superinfection complicating an initial viral illness.

Nasal congestion, rhinorrhoea, sore throat, cough, low grade fever and malaise, in variable combination and severity, characterise the typical presentation, with symptoms generally peaking within two to three days and resolving over seven to ten days, though cough can persist longer.

Features suggesting a specific localised process rather than generalised upper respiratory tract infection include:

• Severe unilateral throat pain with tonsillar exudate and fever (suggesting bacterial pharyngitis).
• Facial pain and purulent nasal discharge persisting beyond ten days (suggesting bacterial sinusitis).
• Hoarseness with a barking cough (suggesting laryngitis or, in children, croup).

Red flag features warranting further assessment include high fever persisting beyond three to four days, severe or worsening symptoms after initial improvement, stridor or significant respiratory distress, inability to swallow secretions, and signs of a deep neck space infection or other complication.

Diagnosis is clinical in the great majority of presentations, based on the characteristic symptom pattern and examination findings, without the need for microbiological confirmation given the predominantly viral, self limiting nature of the illness.

Rapid streptococcal antigen testing or throat culture is considered where bacterial pharyngitis is clinically suspected, guided by a validated clinical scoring system, rather than applied universally to every sore throat.

Further investigation (chest radiograph, blood tests, specific viral testing) is reserved for atypical presentations, immunocompromised patients, or where a specific complication or alternative diagnosis is suspected, rather than performed routinely for uncomplicated upper respiratory tract infection.

Symptomatic and supportive treatment forms the mainstay for the great majority of presentations, including adequate hydration, rest, simple analgesia and antipyretics (paracetamol or a nonsteroidal anti inflammatory drug), and saline nasal irrigation or decongestants for nasal symptoms.

Antibiotics are not indicated for uncomplicated viral upper respiratory tract infection and should be withheld, with clear explanation to the patient regarding the viral aetiology and expected natural course, supporting antimicrobial stewardship and managing expectations that frequently drive requests for antibiotics.

Specific antibiotic treatment is reserved for confirmed or strongly suspected bacterial infection according to the specific syndrome (streptococcal pharyngitis, bacterial sinusitis meeting defined criteria).

Safety netting advice is an important component of managing the large majority of self limiting presentations without unnecessary follow up or investigation. It explains the expected duration of symptoms and specific features that should prompt return for reassessment (worsening rather than improving symptoms, high fever persisting beyond several days, breathing difficulty).