What causes the common cold?

The common cold is caused primarily by viruses that infect the upper respiratory tract. Rhinoviruses account for about half of cases; other agents include endemic coronaviruses, respiratory syncytial virus, adenoviruses, and enteroviruses. These pathogens spread when infected people release respiratory droplets and aerosols during coughing, sneezing, or talking, and by touching contaminated surfaces (fomites) then the face. Close contact, crowded indoor settings, and reduced humidity in colder months increase transmission.

After exposure, viruses attach to and enter nasal and throat epithelial cells, triggering an innate immune response. Symptoms result more from the body’s inflammatory reaction than direct tissue destruction. Typical signs include nasal congestion, runny nose, sore throat, sneezing, cough, and mild malaise; fever is uncommon in adults but may occur in children and is generally low-grade (above 100.4°F [38°C]).

Prevention focuses on interrupting spread: frequent handwashing, respiratory etiquette, surface disinfection, avoiding close contact with sick individuals, and staying home when symptomatic. Vaccination has greatly reduced other respiratory illnesses, but a broadly effective vaccine against the common cold remains elusive because of the large number of viral types and their ability to mutate.

Management is supportive. Rest, adequate hydration, saline nasal irrigation, humidified air, decongestants, and analgesics can ease symptoms. Antibiotics are not effective unless a secondary bacterial complication develops. Most adults recover within a week; if symptoms worsen, shortness of breath, prolonged high fever, or signs of dehydration appear, medical evaluation is advisable.

Incubation typically spans 1–3 days, and most episodes resolve in 7–10 days, though cough can linger longer. Young children experience several colds annually because of immature immunity and frequent close contact in daycare or school. Tobacco exposure and conditions that weaken immune function increase susceptibility and can prolong recovery and fatigue.

Clear, evidence-based communication and appropriate hygiene remain the most reliable defenses against common cold spread.