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Cough by Rick Alan

Definition

A cough is a sudden expulsion of air from the lungs. Its purpose is usually to clear secretions and inhaled foreign substances from the lungs and respiratory tract.

There are different types of cough:

Acute cough—lasts for less than three weeks
Subacute cough—lasts 3-8 weeks
Chronic cough—lasts longer than eight weeks

Causes

An acute cough is usually caused by an infection, such as a cold or flu . In some cases, an acute cough can be the sign of other conditions, such as:

Exposure to an irritant or an allergen
Aspiration of a foreign body
Bronchitis
Pneumonia

Subacute cough is often a cough that follows a respiratory infection. It can also be caused be exposure to irritants or to anything that can cause chronic cough.

A chronic cough can be caused by many factors. Common examples include:

Chronic obstructive pulmonary disease (COPD) (eg, chronic bronchitis , emphysema )
Asthma
Reflux of acid from the stomach into the throat (gastroesophageal reflux disease [GERD])
Postnasal drip, which may be due to:
- Repeated inhalation of environmental irritants
- Sinus inflammation
- Allergies
Bronchiectasis (a less common cause)
Certain medicines (eg, ACE inhibitors)

Alveoli (Air Sacs) of Lung

Risk Factors

The main risk factor for cough is being exposed to irritants, for example:

Tobacco smoke
Noxious fumes
Allergens, such as pollen and dust
Smog and other environmental pollutants

Smoking is a major risk for serious conditions linked to chronic cough, including lung cancer and COPD.

Symptoms

A cough can be a symptom of an underlying condition.

Coughs can be productive or dry. You may find that your cough is worse when waking up and during the night while lying down.

When Should I Call My Doctor?

Call your doctor if you have:

Acute cough that worsens or does not go away on its own
Chronic cough
Signs of an infection (eg, fever, chills)
Cough with wheezing
Blood in the sputum

When Should I Call for Medical Help Immediately?

Call for medical help or go to the emergency room right away if your cough is accompanied by:

Pink or frothy sputum
Trouble breathing
Chest pain
Rapid heartbeat
Swelling in the legs

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam.

Acute cough is usually diagnosed by its accompanying symptoms.

During the diagnosis, your doctor will look for symptoms that suggest an underlying cause. Tests may include:

Chest x-rays —a test that uses radiation to take a picture of structures inside of the chest
Computed tomography (CT) scan of the chest—a type of x-ray that uses a computer to create images of structures inside of the chest
Analysis of a sputum sample
Blood test to check for infection
Skin tests if allergies are suspected
Skin test for tuberculosis
Pulmonary function tests —to measure lung volumes and air flow rates
Bronchoscopy —insertion of a long, thin instrument to view the interior of the airways and collect samples

Treatment

The best treatment for a cough is to treat the underlying condition.

Medication

There are many over-the-counter (OTC) cough and cold products available. Examples include decongestants, expectorants, antihistamines, and antitussives (cough suppressants).

Note: The Food and Drug Administration (FDA) recommends against using OTC cough and cold products to treat infants and children younger than four years old. Rare but serious side effects have been reported, including death, convulsions, and rapid heart rate.

Lifestyle Changes

Consider putting a steam vaporizer or cool-mist humidifier in your room. This type of moisture therapy may help to make secretions looser and easier to cough up.

If you smoke, talk to your doctor about strategies to quit. Smoking affects your lung function and increases your risk of many diseases.

If you are diagnosed with a cough, follow your doctor's instructions .

Prevention

To help avoid a cough:

Be a nonsmoker.
Get proper treatment for the underlying condition.
When working in areas where noxious fumes or airborne substances are present:
- Be sure the area is properly ventilated.
- Wear a protective mask or respirator.

RESOURCES:

American Academy of Family Physicians http://www.aafp.org/
American Lung Association http://www.lung.org/

CANADIAN RESOURCES:

The Canadian Lung Association http://www.lung.ca/
Health Canada http://www.hc-sc.gc.ca/

References:

American Academy of Family Physicians website. Available at: http://www.aafp.org .
American College of Chest Physicians website. Available at: http://www.chestnet.org .
Chronic cough: lifestyle and home remedies. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/chronic-cough/DS00957/DSECTION=lifestyle-and-home-remedies . Updated May 14, 2011. Accessed January 11, 2012.
Cough. Family Doctor.org. website. Available at: http://familydoctor.org/familydoctor/en/health-tools/search-by-symptom/cough.html . Accessed January 11, 2012.
The Merck Manual of Medical Information (online version). 2nd ed. 2005.
Practice guideline—cough: diagnosis and management. American Family Physician website. Available at: http://www.aafp.org/afp/2007/0215/p567.html . Published February 15, 2007. Accessed January 12, 2012.
1/30/2008 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Public health advisory: Nonprescription cough and cold medicine use in children—FDA recommends that over-the-counter (OTC) cough and cold products not be used for infants and children under 2 years of age. US Food and Drug Administration website. Available at: http://www.fda.gov/cder/drug/advisory/cough_cold_2008.htm . Accessed January 30, 3008.
1/30/2008 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Paul IM, Beiler J, McMonagle A, Shaffer ML, Duda L, Berlin CM Jr. Effect of honey, dextromethorphan, and no treatment on nocturnal cough and sleep quality for coughing children and their parents. Arch Pediatr Adolesc Med. 2007;161:1149-1153.
11/12/2010 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Smith S, Schroeder K, Fahey T. Over-the-counter (OTC) medications for acute cough in children and adults in ambulatory settings. Cochrane Database Syst Rev. 2010;(9):CD001831.

Last reviewed September 2012 by Brian Randall, MD

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