common cold common cold the common cold or the cold is a viral infectious disease of the upper respiratory tract that primarily affects the respiratory mucosa of the nose, throat, sinuses, and larynx. signs and symptoms may appear fewer than two days after exposure to the virus. these may include coughing, sore throat, runny nose, sneezing, headache, and fever. people usually recover in seven to ten days, but some symptoms may last up to three weeks. occasionally, those with other health problems may develop pneumonia. not to be confused with influenza. common coldother namescold, acute viral nasopharyngitis, nasopharyngitis, viral rhinitis, rhinopharyngitis, acute coryza, head cold, upper respiratory tract infection (urti)a representation of the molecular surface of one variant of human rhinovirusspecialtyinfectious diseasesymptomscough, sore throat, runny nose, fevercomplicationsusually none, but occasionally otitis media, sinusitis, pneumonia and sepsis can occurusual onset~2 days from exposureduration1–3 weekscausesviral (usually rhinovirus)diagnostic methodbased on symptomsdifferential diagnosisallergic rhinitis, bronchitis, bronchiolitis, pertussis, sinusitispreventionhand washing, cough etiquette, social distancing, vitamin ctreatmentsymptomatic therapy, zincmedicationnsaidsfrequency2–3 per year (adults) 6–8 per year (children) well over 200 virus strains are implicated in causing the common cold, with rhinoviruses, coronaviruses, adenoviruses and enteroviruses being the most common. they spread through the air during close contact with infected people or indirectly through contact with objects in the environment, followed by transfer to the mouth or nose. risk factors include going to child care facilities, not sleeping well, and psychological stress. the symptoms are mostly due to the body's immune response to the infection rather than to tissue destruction by the viruses themselves. the symptoms of influenza are similar to those of a cold, although usually more severe and less likely to include a runny nose. there is no vaccine for the common cold. the primary methods of prevention are hand washing; not touching the eyes, nose or mouth with unwashed hands; and staying away from sick people. some evidence supports the use of face masks. there is also no cure, but the symptoms can be treated. zinc may reduce the duration and severity of symptoms if started shortly after the onset of symptoms. nonsteroidal anti-inflammatory drugs (nsaids) such as ibuprofen may help with pain. antibiotics, however, should not be used, as all colds are caused by viruses, and there is no good evidence that cough medicines are effective. the common cold is the most frequent infectious disease in humans. under normal circumstances, the average adult gets two to three colds a year, while the average child may get six to eight. infections occur more commonly during the winter. these infections have existed throughout human history. signs and symptoms woman with symptoms of the common cold the typical symptoms of a cold include cough, runny nose, sneezing, nasal congestion, and a sore throat, sometimes accompanied by muscle ache, fatigue, headache, and loss of appetite. a sore throat is present in about 40% of cases, a cough in about 50%, and muscle ache likewise in about 50%. in adults, a fever is generally not present but it is common in infants and young children. the cough is usually mild compared to that accompanying influenza. while a cough and a fever indicate a higher likelihood of influenza in adults, a great deal of similarity exists between these two conditions. a number of the viruses that cause the common cold may also result in asymptomatic infections. the color of the mucus or nasal secretion may vary from clear to yellow to green and does not indicate the class of agent causing the infection. progression cold symptoms over time a cold usually begins with fatigue, a feeling of being chilled, sneezing, and a headache, followed in a couple of days by a runny nose and cough. symptoms may begin within sixteen hours of exposure and typically peak two to four days after onset. they usually resolve in seven to ten days, but some can last for up to three weeks. the average duration of cough is eighteen days and in some cases people develop a post-viral cough which can linger after the infection is gone. in children, the cough lasts for more than ten days in 35–40% of cases and continues for more than 25 days in 10%. causes viruses coronaviruses are a group of viruses known for causing the common cold. they have a halo or crown-like (corona) appearance when viewed under an electron microscope. the common cold is an infection of the upper respiratory tract which can be caused by many different viruses. the most commonly implicated is a rhinovirus (30–80%), a type of picornavirus with 99 known serotypes. other commonly implicated viruses include human coronaviruses (≈ 15%), influenza viruses (10–15%), adenoviruses (5%), human respiratory syncytial virus (rsv), enteroviruses other than rhinoviruses, human parainfluenza viruses, and human metapneumovirus. frequently more than one virus is present. in total, more than 200 viral types are associated with colds. transmission the common cold virus is typically transmitted via airborne droplets (aerosols), direct contact with infected nasal secretions, or fomites (contaminated objects). which of these routes is of primary importance has not been determined. the viruses may survive for prolonged periods in the environment (over 18 hours for rhinoviruses) and can be picked up by people's hands and subsequently carried to their eyes or nose where infection occurs. transmission from animals is considered highly unlikely; an outbreak documented at a british scientific base on adelaide island after seventeen weeks of isolation was thought to have been caused by transmission from a contaminated object or an asymptomatic human carrier, rather than from the husky dogs which were also present at the base. transmission is common in daycare and at school due to the proximity of many children with little immunity and frequently poor hygiene. these infections are then brought home to other members of the family. there is no evidence that recirculated air during commercial flight is a method of transmission. people sitting close to each other appear to be at greater risk of infection. rhinovirus-caused colds are most infectious during the first three days of symptoms; they are much less infectious afterwards. weather a common misconception is that one can "catch a cold" merely through prolonged exposure to cold weather. although it is now known that colds are viral infections, the prevalence of many such viruses are indeed seasonal, occurring more frequently during cold weather. the reason for the seasonality has not been conclusively determined. possible explanations may include cold temperature-induced changes in the respiratory system, decreased immune response, and low humidity causing an increase in viral transmission rates, perhaps due to dry air allowing small viral droplets to disperse farther and stay in the air longer. the apparent seasonality may also be due to social factors, such as people spending more time indoors, near infected people, and specifically children at school. although normal exposure to cold does not increase one's risk of infection, severe exposure leading to significant reduction of body temperature (hypothermia) may put one at a greater risk for the common cold; although controversial, the majority of evidence suggests that it may increase susceptibility to infection. other herd immunity, generated from previous exposure to cold viruses, plays an important role in limiting viral spread, as seen with younger populations that have greater rates of respiratory infections. poor immune function is a risk factor for disease. insufficient sleep and malnutrition have been associated with a greater risk of developing infection following rhinovirus exposure; this is believed to be due to their effects on immune function. breast feeding decreases the risk of acute otitis media and lower respiratory tract infections among other diseases, and it is recommended that breast feeding be continued when an infant has a cold. in the developed world breast feeding may not be protective against the common cold in and of itself. pathophysiology the common cold is a disease of the upper respiratory tract. the symptoms of the common cold are believed to be primarily related to the immune response to the virus. the mechanism of this immune response is virus-specific. for example, the rhinovirus is typically acquired by direct contact; it binds to humans via icam-1 receptors and the cdhr3 receptor through unknown mechanisms to trigger the release of inflammatory mediators. these inflammatory mediators then produce the symptoms. it does not generally cause damage to the nasal epithelium. the respiratory syncytial virus (rsv), on the other hand, is contracted by direct contact and airborne droplets. it then replicates in the nose and throat before frequently spreading to the lower respiratory tract. rsv does cause epithelium damage. human parainfluenza virus typically results in inflammation of the nose, throat, and bronchi. in young children, when it affects the trachea, it may produce the symptoms of croup, due to the small size of their airways. diagnosis the distinction between viral upper respiratory tract infections is loosely based on the location of symptoms, with the common cold affecting primarily the nose (rhinitis), throat (pharyngitis), and lungs (bronchitis). there can be significant overlap, and more than one area can be affected. self-diagnosis is frequent. isolation of the viral agent involved is rarely performed, and it is generally not possible to identify the virus type through symptoms. prevention the only useful ways to reduce the spread of cold viruses are physical measures such as using correct hand washing technique and face masks; in the healthcare environment, gowns and disposable gloves are also used. isolation or quarantine is not used as the disease is so widespread and symptoms are non-specific. there is no vaccine to protect against the common cold. vaccination has proven difficult as there are many viruses involved and they mutate rapidly. creation of a broadly effective vaccine is, therefore, highly improbable. regular hand washing appears to be effective in reducing the transmission of cold viruses, especially among children. whether the addition of antivirals or antibacterials to normal hand washing provides greater benefit is unknown. wearing face masks when around people who are infected may be beneficial; however, there is insufficient evidence for maintaining a greater social distance. it is unclear whether zinc supplements affect the likelihood of contracting a cold. routine vitamin c supplements do not reduce the risk or severity of the common cold, though they may reduce its duration. gargling with water was found useful in one small trial. management poster from 1937 encouraging citizens to "consult your physician" for treatment of the common cold treatments of the common cold primarily involve medications and other therapies for symptomatic relief. getting plenty of rest, drinking fluids to maintain hydration, and gargling with warm salt water are reasonable conservative measures. much of the benefit from symptomatic treatment is, however, attributed to the placebo effect. as of 2010, no medications or herbal remedies had been conclusively demonstrated to shorten the duration of infection. symptomatic various treatments for the common cold - liquid and pill cold medicine, tea, throat lozenges, and over-the-counter decongestants. treatments that may help with symptoms include simple pain medication and medications for fevers such as ibuprofen and acetaminophen (paracetamol). however, it is not clear whether acetaminophen helps with symptoms. it is not known if over the counter cough medications are effective for treating an acute cough. cough medicines are not recommended for use in children due to a lack of evidence supporting effectiveness and the potential for harm. in 2009, canada restricted the use of over-the-counter cough and cold medication in children six years and under due to concerns regarding risks and unproven benefits. the misuse of dextromethorphan (an over-the-counter cough medicine) has led to its ban in a number of countries. intranasal corticosteroids have not been found to be useful. in adults short term use of nasal decongestants may have a small benefit. antihistamines may improve symptoms in the first day or two; however, there is no longer-term benefit and they have adverse effects such as drowsiness. other decongestants such as pseudoephedrine appear effective in adults. combined oral analgesics, antihistaminics and decongestants are generally effective for older children and adults. ipratropium nasal spray may reduce the symptoms of a runny nose but has little effect on stuffiness. ipratropium may also help with cough in adults. the safety and effectiveness of nasal decongestant use in children is unclear. due to lack of studies, it is not known whether increased fluid intake improves symptoms or shortens respiratory illness.