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
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)
- 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
- Bronchiectasis (a less common cause)
- Certain medicines (eg, ACE inhibitors)
Alveoli (Air Sacs) of Lung
Copyright © Nucleus Medical Media, Inc.
Last reviewedSeptember 2012by Brian Randall, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.