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Common Cold

(Upper Respiratory Infection; Coryza)

By Craig R. Pringle, BSc, PhD, Professor Emeritus, School of Life Sciences, University of Warwick

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The common cold is an acute, usually afebrile, self-limited viral infection causing upper respiratory symptoms, such as rhinorrhea, cough, and sore throat. Diagnosis is clinical. Handwashing helps prevent its spread. Treatment is supportive.

About 50% of all colds are caused by one of the > 100 serotypes of rhinoviruses. Coronaviruses cause some outbreaks, and infections caused by influenza and parainfluenza viruses, enterovirus, adenovirus, respiratory syncytial viruses, and metapneumoviruses may also manifest as the common cold, particularly in patients who are experiencing reinfection.

Rhinovirus infections are most common during fall and spring and are less common during winter. Rhinoviruses are most efficiently spread by direct person-to-person contact, although spread may also occur via large-particle aerosols.

The most potent deterrent to infection is the presence of specific neutralizing antibodies in the serum and secretions, induced by previous exposure to the same or a closely related virus. Susceptibility to colds is not affected by exposure to cold temperature, host health and nutrition, or upper respiratory tract abnormalities (eg, enlarged tonsils or adenoids).

Symptoms and Signs

After an incubation period of 24 to 72 h, symptoms begin with a scratchy or sore throat, followed by sneezing, rhinorrhea, nasal obstruction, and malaise. Temperature is usually normal, particularly when the pathogen is a rhinovirus or coronavirus. Nasal secretions are watery and profuse during the first days but then become more mucoid and purulent. Mucopurulent secretions do not indicate a bacterial superinfection. Cough is usually mild but often lasts into the 2nd wk. Most symptoms due to uncomplicated colds resolve within 10 days. Colds may exacerbate asthma and chronic bronchitis.

Purulent sputum or significant lower respiratory tract symptoms are unusual with rhinovirus infection. Purulent sinusitis and otitis media may result from the viral infection itself or from secondary bacterial infection.


  • Clinical evaluation

Diagnosis is generally made clinically and presumptively, without diagnostic tests. Allergic rhinitis is the most important consideration in differential diagnosis.


  • Symptomatic treatment

No specific treatment exists. Antipyretics and analgesics may relieve fever and sore throat. Nasal decongestants may reduce nasal obstruction. Topical nasal decongestants are more effective than oral decongestants, but the use of topical drugs for > 3 to 5 days may result in rebound congestion. Rhinorrhea may be relieved with 1st-generation antihistamines (eg, chlorpheniramine) or intranasal ipratropium bromide (2 sprays of a 0.03% solution bid or tid); however, these drugs should be avoided in the elderly and people with benign prostatic hypertrophy or glaucoma. First-generation antihistamines frequently cause sedation, but 2nd-generation (nonsedating) antihistamines are ineffective for treating the common cold. Antihistamines and decongestants are not recommended for children < 4 yr.

Zinc, echinacea, and vitamin C have all been evaluated as common cold therapies, but none has been clearly shown to be beneficial.


There are no vaccines. Polyvalent bacterial vaccines, citrus fruits, vitamins, ultraviolet light, glycol aerosols, and other folk remedies do not prevent the common cold. Handwashing and use of surface disinfectant in a contaminated environment may reduce spread of infection.

Antibiotics should not be given unless there is clear evidence of secondary bacterial infection. In patients with chronic lung disease, antibiotics may be given with less restriction.