About 50% of all colds are caused by one of the > 100 serotypes of rhinoviruses. Coronaviruses Coronaviruses and Acute Respiratory Syndromes (MERS and SARS) Coronaviruses are enveloped RNA viruses that cause respiratory illnesses of varying severity from the common cold to fatal pneumonia. Numerous coronaviruses, first discovered in domestic poultry... read more cause some outbreaks, and infections caused by influenza viruses Influenza Influenza is a viral respiratory infection causing fever, coryza, cough, headache, and malaise. Mortality is possible during seasonal epidemics, particularly among high-risk patients (eg, those... read more , parainfluenza viruses Parainfluenza Virus Infections Parainfluenza viruses include several closely related viruses that cause many respiratory illnesses varying from the common cold to an influenza-like syndrome or pneumonia; croup is the most... read more , enteroviruses Overview of Enterovirus Infections Enteroviruses, along with rhinoviruses (see Common Cold) and human parechoviruses, are a genus of picornaviruses (pico, or small, RNA viruses). All enteroviruses are antigenically heterogeneous... read more , adenoviruses Adenovirus Infections Infection with one of the many adenoviruses may be asymptomatic or result in specific syndromes, including mild respiratory infections, keratoconjunctivitis, gastroenteritis, cystitis, and primary... read more , respiratory syncytial viruses Respiratory Syncytial Virus (RSV) and Human Metapneumovirus Infections Respiratory syncytial virus and human metapneumovirus infections cause seasonal lower respiratory tract disease, particularly in infants and young children. Disease may be asymptomatic, mild... read more , 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 of Common Cold
After an incubation period of 24 to 72 hours, cold 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 week. Most symptoms due to uncomplicated colds resolve within 10 days.
Colds may exacerbate asthma Asthma Asthma is a disease of diffuse airway inflammation caused by a variety of triggering stimuli resulting in partially or completely reversible bronchoconstriction. Symptoms and signs include dyspnea... read more and chronic bronchitis Chronic Obstructive Pulmonary Disease (COPD) .
Purulent sputum or significant lower respiratory tract symptoms are unusual with rhinovirus infection. Purulent sinusitis Sinusitis Sinusitis is inflammation of the paranasal sinuses due to viral, bacterial, or fungal infections or allergic reactions. Symptoms include nasal obstruction and congestion, purulent rhinorrhea... read more and otitis media Otitis Media (Acute) Acute otitis media is a bacterial or viral infection of the middle ear, usually accompanying an upper respiratory infection. Symptoms include otalgia, often with systemic symptoms (eg, fever... read more may result from the viral infection itself or from secondary bacterial infection.
Diagnosis of Common Cold
Diagnosis of the common cold is generally made clinically and presumptively, without diagnostic tests, although polymerase chain reaction (PCR) testing is available in many multiplex platforms.
Allergic rhinitis Allergic Rhinitis Allergic rhinitis is seasonal or perennial itching, sneezing, rhinorrhea, nasal congestion, and sometimes conjunctivitis, caused by exposure to pollens or other allergens. Diagnosis is by history... read more is the most important consideration in differential diagnosis.
Treatment of Common Cold
No specific treatment for the common cold 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 2 or 3 times a day); however, these drugs offer minimal benefit and should be used with caution in older patients, people with benign prostatic hypertrophy, or angle-closure 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 years.
Zinc Zinc Supplements Zinc, a mineral, is required in small quantities (adult RDA of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified cereals. (See also Overview... read more , echinacea Echinacea Echinacea, a North American wildflower, contains a variety of biologically active substances. (See also Overview of Dietary Supplements.) Echinacea is said to stimulate the immune system. When... read more , and vitamin C have all been evaluated as common cold therapies, but none has been clearly shown to be beneficial.
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.
Prevention of Common Cold
There are no vaccines for the common cold.
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.
Many viruses can cause the common cold; rhinoviruses cause about half of colds.
Susceptibility to colds is not affected by exposure to cold, host health and nutrition, or the presence of upper respiratory tract abnormalities.
Antihistamines may be used to relieve rhinorrhea, but they offer minimal benefit and should be used with caution in older patients and avoided in children < 4 years.
Topical and oral decongestants relieve nasal obstruction, but repeated use may cause rebound congestion.
Many substances have been evaluated for prevention and treatment, but none has clearly been shown to be beneficial.