Common Cold

An acute, self limiting viral infection of the upper respiratory tract, predominantly caused by rhinovirus, representing the most frequent acute illness in humans and a leading cause of work and school absence, with management centred entirely on symptomatic relief given the absence of any specific antiviral treatment.

Aetiology

Rhinovirus accounts for the majority of cases, with coronaviruses, respiratory syncytial virus, parainfluenza and adenovirus contributing to the remainder. Transmission occurs through respiratory droplets and direct contact with contaminated surfaces followed by self inoculation of the nasal or conjunctival mucosa, explaining the importance of hand hygiene in prevention.

Rhinorrhoea, initially clear and watery before becoming thicker and sometimes discoloured as the illness progresses (a normal part of the immune response rather than an indicator of bacterial superinfection requiring antibiotics, an important point of patient education), nasal congestion, sneezing and sore throat characterise the typical onset.

Mild cough, low grade fever (more common in children than adults), headache and general malaise frequently accompany the nasal symptoms, with symptoms typically peaking at two to three days and resolving over seven to ten days, though cough can persist for up to three weeks in a proportion of patients.

The absence of high fever, severe systemic symptoms or focal findings (unlike influenza, which typically produces more abrupt onset and severe systemic symptoms) is characteristic and helps distinguish the common cold clinically from other respiratory viral illnesses, though considerable overlap exists.

Diagnosis is entirely clinical, based on the characteristic symptom pattern, with no laboratory or microbiological testing required or indicated for uncomplicated presentations.

Discoloured nasal discharge alone, in the absence of other features suggesting bacterial sinusitis (persistent symptoms beyond ten days, worsening after initial improvement, severe facial pain), does not indicate bacterial infection and should not prompt antibiotic treatment, a common source of misunderstanding among both patients and clinicians.

Supportive care, including adequate hydration, rest and simple analgesia or antipyretics for discomfort or fever, forms the entirety of evidence based management, since no treatment has been shown to substantially shorten the natural course of the illness.

Saline nasal irrigation or sprays provide symptomatic relief of congestion without the rebound congestion risk associated with prolonged use of topical decongestants, which should be limited to short term use of a few days if used at all.

Zinc lozenges, taken within the first day of symptom onset, have some evidence for modestly reducing symptom duration, though evidence quality is mixed and effect size modest.

Antibiotics have no role in the treatment of the common cold and should not be prescribed, given the viral aetiology and the absence of any benefit, alongside the broader public health imperative of antimicrobial stewardship.

Reassurance regarding the self limiting nature of the illness, together with clear guidance on when to seek further assessment (symptoms persisting or worsening beyond ten days, high fever, breathing difficulty, or symptoms in a young infant or immunocompromised individual), completes appropriate management for the great majority of presentations.

Hand hygiene and respiratory etiquette (covering coughs and sneezes) remain the most effective measures for reducing transmission to others, given the absence of a specific vaccine or definitive preventive treatment for this group of viruses.