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
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
- Acute bronchitis
Subacute cough is often a cough that follows a respiratory infection. It can also be caused by exposure to irritants or to anything that can cause chronic cough.
A chronic cough has many causes. Common examples include:
- Chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis or emphysema
- Acid reflux from the stomach into the esophagus, a condition called gastroesophageal reflux disease (GERD)
- Postnasal drip, which may be due to:
- Repeated inhalation of environmental irritants
- Sinus inflammation
- Certain medications, such as ACE inhibitors
Alveoli (Air Sacs) of Lung
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Factors that may increase your risk of developing a cough include:
- 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.
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.
Call your doctor if you have:
- Acute cough that worsens or does not go away on its own
- Cough lasting more than eight weeks
- Signs of an infection, including fever and chills
- Cough with wheezing
- Blood in the sputum
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
The doctor will ask about your symptoms and medical history. A physical exam will be done.
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:
- Blood test to check for infection
- Skin tests if allergies are suspected
- Analysis of a sputum sample
- Skin test for tuberculosis
- Pulmonary function tests—to test lung function and capacity
- Bronchoscopy—insertion of a long, thin instrument to view the interior of the airways and collect samples
Imaging tests take pictures of internal body structures. These can be done with a chest x-ray or a chest CT scan.
The best treatment for a cough is to treat the underlying condition.
There are many over-the-counter (OTC) cough and cold products available. These include decongestants, expectorants, antihistamines, and antitussives.
Note: Cough and cold medicines in should not be used in children under 2 years old, and they are not recommended in children under 4 years old. The US Food and Drug Administration has not completed its review regarding the safety of over-the-counter cough and cold medicines in children ages 2-11 years. Rare, but serious side effects have been reported.
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 are diagnosed with a cough, follow your doctor's instructions.
To reduce your chances of developing a cough:
- Talk to your doctor about strategies to quit smoking. Smoking affects your lung function and increases your risk of many diseases.
- 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.