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Coughs - Topic OverviewCoughing is the body's way of removing foreign material or mucus from the lungs and upper airway passages   or of reacting to an irritated airway. Coughs have distinctive traits you can learn to recognize. A cough is only a symptom, not a disease, and often the importance of your cough can be determined only when other symptoms are evaluated.

For information about coughs in children, see the topic Coughs, Age 11 and Younger.

Productive coughs

A productive cough produces phlegm or mucus (sputum). The mucus may have drained down the back of the throat from the nose or sinuses or may have come up from the lungs. A productive cough generally should not be suppressed-it clears mucus from the lungs. There are many causes of a productive cough, such as:

Viral illnesses. It is normal to have a productive cough when you have a common cold. Coughing is often triggered by mucus that drains down the back of the throat.

Infections. An infection of the lungs or upper airway passages can cause a cough. A productive cough may be a symptom of pneumonia, bronchitis,sinusitis, or tuberculosis.

Chronic lung disease. A productive cough could be a sign that a disease such aschronic obstructive pulmonary disease (COPD) is getting worse or that you have an infection.

Stomach acid backing up into the esophagus  . This type of coughing may be a symptom of gastroesophageal reflux disease (GERD) and may awaken you from sleep.

Nasal discharge (postnasal drip) draining down the back of the throat. This can cause a productive cough or the feeling that you constantly need to clear your throat. Experts disagree about whether a postnasal drip or the viral illness that caused it is responsible for the cough.

Smoking or other tobacco use. Productive coughs in a person who smokes or uses other forms of tobacco is often a sign of lung damage or irritation of the throat or esophagus.

Nonproductive coughs

A nonproductive cough is dry and does not produce sputum. A dry, hacking cough may develop toward the end of a cold or after exposure to an irritant, such as dust or smoke. There are many causes of a nonproductive cough, such as:

Viral illnesses. After a common cold, a dry cough may last several weeks longer than other symptoms and often gets worse at night.

Bronchospasm. A nonproductive cough, particularly at night, may mean spasms in the bronchial tubes (bronchospasm) caused by irritation.

Allergies. Frequent sneezing is also a common symptom of allergic rhinitis. Medicines called ACE inhibitors that are used to control high blood pressure.

Examples of ACE inhibitors include captopril (Capoten), enalapril maleate (Vasotec), and lisinopril (Prinivil, Zestril, or Zestoretic).

Exposure to dust, fumes, and chemicals in the work environment. Asthma. A chronic dry cough may be a sign of mild asthma. Other symptoms

may include wheezing, shortness of breath, or a feeling of tightness in the chest. For more information, see the topic Asthma in Teens and Adults.

Blockage of the airway by an inhaled object, such as food or a pill. For more information, see the topic Swallowed Objects.

Many coughs are caused by a viral illness. Antibiotics are not used to treat viral illnesses and do not alter the course of viral infections. Unnecessary use of an antibiotic exposes you to the risks of anallergic reaction and antibiotic side effects, such as nausea, vomiting, diarrhea, rashes, and yeast infections. Antibiotics also may kill beneficial bacteria and encourage the development of dangerous antibiotic-resistant bacteria.

A careful evaluation of your health may help you identify other symptoms. Remember, a cough is only a symptom, not a disease, and often the importance of your cough can only be determined when other symptoms are evaluated. Coughs occur with bacterial and viral respiratory infections. If you have other symptoms, such as a sore throat, sinus pressure, or ear pain, see the Related Topics section.

Use the Check Your Symptoms section to decide if and when you should see a doctor.

Signs and symptoms

The typical symptoms of a cold include cough, runny nose, nasal congestion and a sore throat,

sometimes accompanied by muscle ache, fatigue, headache, and loss of appetite.[1] A sore throat is

present in about 40% of the cases and a cough in about 50%,[2] while muscle ache occurs in about half.

[3] In adults, a fever is generally not present but it is common in infants and young children.[3] The cough is

usually mild compared to that accompanying influenza.[3] While a cough and a fever indicate a higher

likelihood of influenza in adults, a great deal of similarity exists between these two conditions.[4] A number

of the viruses that cause the common cold may also result in asymptomatic infections.[5][6] The color of

the sputum or nasal secretion may vary from clear to yellow to green and does not predict the class of

agent causing the infection.[7]

Progression

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.[1] Symptoms may begin within 16 hours of exposure[8] and

typically peak two to four days after onset.[3][9] They usually resolve in seven to ten days but some can last

for up to three weeks.[10] In children, the cough lasts for more than ten days in 35–40% of the cases and

continues for more than 25 days in 10%.[11]

Cause

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 a viral infection of the upper respiratory tract. The most commonly implicated virus is

a rhinovirus (30–80%), a type of picornaviruswith 99 known serotypes.[12][13] Others

include: coronavirus (10–15%), human parainfluenza viruses, human respiratory syncytial

virus, adenoviruses,enteroviruses, and metapneumovirus.[14] Frequently more than one virus is present.

[15] In total over 200 different viral types are associated with colds.[3]

Transmission

The common cold virus is typically transmitted via airborne droplets (aerosols), direct contact with infected

nasal secretions, or fomites (contaminated objects).[2][16] Which of these routes is of primary importance

has not been determined, however hand-to-hand and hand-to-surface-to-hand contact seems of more

importance than transmission via aerosols.[17] 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.[16] Transmission is common in daycare and at school

due to the proximity of many children with little immunity and frequently poor hygiene.[18] These infections

are then brought home to other members of the family.[18] There is no evidence that recirculated air during

commercial flight is a method of transmission.[16]However, people sitting in proximity appear at greater

risk.[17] Rhinovirus-caused colds are most infectious during the first three days of symptoms; they are

much less infectious afterwards.[19]

Weather

The traditional folk theory is that a cold can be "caught" by prolonged exposure to cold weather such as

rain or winter conditions, which is how the disease got its name.[20] The role of body cooling as a risk

factor for the common cold is controversial.[21] Some of the viruses that cause the common colds are

seasonal, occurring more frequently during cold or wet weather.[22] Some believe this to be due primarily

to increased time spent indoors in proximity;[23] specifically children returning to school.[18] However, it may

also be related to changes in the respiratory system that result in greater susceptibility.[23] Low humidity

increases viral transmission rates potentially due to dry air allowing small viral droplets to disperse farther

and stay in the air longer.[24]

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.[25] Poor

immune function is also a risk factor for disease.[25][26] 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.[27][28]

Pathophysiology

The common cold is a disease of theupper respiratory tract.

The symptoms of the common cold are believed to be primarily related to the immune response to the

virus.[29] The mechanism of this immune response is virus specific. For example, the rhinovirus is typically

acquired by direct contact; it binds to human ICAM-1 receptors through unknown mechanisms to trigger

the release of inflammatory mediators.[29] These inflammatory mediators then produce the symptoms.[29] It

does not generally cause damage to the nasal epithelium.[3] The respiratory syncytial virus (RSV) on the

other hand is contracted by both direct contact and airborne droplets. It then replicates in the nose and

throat before frequently spreading to the lower respiratory tract.[30] RSV does cause epithelium damage.

[30]Human parainfluenza virus typically results in inflammation of the nose, throat, and bronchi.[31] In young

children when it affects the trachea it may produce the symptoms of croup due to the small size of their

airway.[31]

Diagnosis

The distinction between different viral upper respiratory tract infections is loosely based on the location of

symptoms with the common cold affecting primarily the nose, pharyngitis the throat, and bronchitis the

lungs.[2] There however can be significant overlap and multiple areas can be affected.[2] The common cold

is frequently defined as nasal inflammation with varying amount of throat inflammation.[32] Self-diagnosis is

frequent.[3] Isolation of the actual viral agent involved is rarely performed,[32] and it is generally not possible

to identify the virus type through symptoms.[3]

Prevention

Physical measures to prevent the spread of cold viruses have been deemed the only potentially effective

measures for prevention.[33] These measures include primarily hand washing and face masks; in the

health care environment, gowns and disposable gloves are also used.[33] Efforts such as quarantine are

not possible as the disease is so widespread and symptoms are non-specific. Vaccination has proved

difficult as there are so many viruses involved and they change rapidly.[33] Creation of a broadly effective

vaccine is thus highly improbable.[34]

Regular hand washing appears to be effective at reducing the transmission of cold viruses especially

among children.[35] Whether the addition of antivirals or antibacterials to normal hand washing provides

greater benefit is unknown.[35] Wearing face masks when around people who are infected may be

beneficial; however, there is insufficient evidence for maintaining a greater social distance.

[35] Zinc supplementation may be effective at decreasing the rate of colds.[36] Routine vitamin

C supplementation does not reduce the risk or severity of the common cold, though it may 

Management

Poster encouraging citizens to "Consult your Physician" for treatment of the common cold

There are currently no medications or herbal remedies which have been conclusively demonstrated to

shorten the duration of infection.[38] Treatment thus comprises symptomatic relief.[39] Getting plenty of rest,

drinking fluids to maintain hydration, and gargling with warm salt water, are reasonable conservative

measures.[14] Much of the benefit from treatment is however attributed to the placebo effect.[40]

Symptomatic

Treatments that help alleviate symptoms include simple analgesics and antipyretics such

as ibuprofen[41] and acetaminophen/paracetamol.[42] Evidence does not show that cough medicines are

any more effective than simple analgesics[43] and they are not recommended for use in children due to a

lack of evidence supporting effectiveness and the potential for harm.[44][45] 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.[44] In adults there is insufficient evidence to support the use of

cough medications.[46] The misuse of dextromethorphan (an over-the-counter cough medicine) has led to

its ban in a number of countries.[47]

In adults the symptoms of a runny nose can be reduced by first-generation antihistamines; however, they

are associated with adverse effects such as drowsiness.[39] Other decongestants such

as pseudoephedrine are also effective in this population.[48] Ipratropium nasal spray may reduce the

symptoms of a runny nose but there is little effect on stuffiness.[49] Second-generation

antihistamines however do not appear to be effective.[50]

Due to lack of studies, it is not known whether increased fluid intake improves symptoms or shortens

respiratory illness[51] and a similar lack of data exists for the use of heated humidified air.[52] One study has

found chest vapor rub to be effective at providing some symptomatic relief of nocturnal cough,

congestion, and sleep difficulty.[53]

Alternative treatments

While there are many alternative treatments used for the common cold, there is insufficient scientific

evidence to support the use of most.[39] As of 2010 there is insufficient evidence to recommend for or

against either honey or nasal irrigation.[58][59] Studies suggested that zinc, if taken within 24 hours of the

onset of symptoms, reduces the duration and severity of the common cold in healthy people.[36] Due to

wide differences between the studies, further research may be needed to determine how and when zinc

may be effective.[60] Vitamin C's effect on the common cold while extensively researched is disappointing,

except in limited circumstances, specifically, individuals exercising vigorously in cold environments.[37]

[61] Evidence about the usefulness ofechinacea is inconsistent.[62][63] Different types of echinacea

supplements may vary in their effectiveness.[62] It is unknown if garlic is effective.[64] A single trial of vitamin

D did not find benefit.[65]

Prognosis

The common cold is generally mild and self-limiting with most symptoms generally improving in a week.

[2] Severe complications, if they occur, are usually in the very old, the very young or those who

are immunosuppressed.[66] Secondary bacterial infections may occur resulting in sinusitis, pharyngitis, or

an ear infection.[67] It is estimated that sinusitis occurs in 8% and an ear infection in 30% of cases.[68]

Epidemiology

The common cold is the most common human disease [66]  and all peoples globally are affected.[18] Adults

typically have two to five infections annually[2][3] and children may have six to ten colds a year (and up to

twelve colds a year for school children).[39] Rates of symptomatic infections increase in the elderly due to a

worsening immune system.[25]