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A cough is a spontaneous reflex. When things such as mucus, germs or dust irritate your throat and airways, your body automatically responds by coughing. Similar to other reflexes such as sneezing or blinking, coughing helps protect your body.

Key Facts

  • Coughing is an important reflex that helps protect your airway and lungs against irritants.
  • Coughing can propel air and particles out of your lungs and throat at speeds close to 50 miles per hour.
  • Occasional coughing is normal as it helps clear your throat and airway of germs, mucus and dust.
  • A cough that doesn’t go away or comes with other symptoms like shortness of breath, mucus production or bloody phlegm could be the sign of a more serious medical problem.

How a Cough Affects Your Body

An occasional cough is a normal healthy function of your body. Your throat and airways are equipped with nerves that sense irritants and seek to dispel them. This response is almost instantaneous and very effective.

Throats and lungs normally produce a small amount of mucus to keep the airway moist and to have a thin covering layer that works as a protective barrier against irritants and germs you may breathe in. Some infrequent coughing helps mobilize mucus and has no damaging effects on your body. Coughing also allows for the rapid removal of any unwelcome particles you accidentally breathe in.

Cough Causes

These are common causes of acute cough – lasting less than two months:

  • Upper respiratory tract infections: Infections of the nose and throat are the most common cause of coughing related to illness. They are usually associated with fevers, sore throat and runny nose. They are almost always caused by viruses, and include the common cold, viral laryngitis and influenza.
  • Hay fever (or allergic rhinitis): A common allergic condition that mimics the symptoms of a common cold. It is usually associated with dry cough, sneezing and runny nose.
  • Inhalation of irritants: Acute exposure to some fumes and vapors can cause inflammation of the throat and airway and cause cough.
  • Lower respiratory tract infections: These are more serious viral and bacterial infections that usually cause a deep, lingering cough and fever. They can affect the airways (bronchitis) or go further into the lungs (pneumonia).
  • Pulmonary embolism: This is a potentially life-threatening condition where a blood clot travels, usually from the legs, to the lungs causing sudden shortness of breath and sometimes a dry cough.
  • Lung collapse (or pneumothorax): This is caused by the deflation of the lung. It can be spontaneous or due to chest trauma. Signs of a collapsed lung include sudden chest pain, dry cough and shortness of breath.
  • Heart failure: A weak or diseased heart can cause buildup of fluid in the lung, causing cough and worsening shortness of breath.
  • Post-nasal drip: This condition shows up as a dry cough caused by the chronic dripping of mucus from the back of the nose to the throat. Usually this occurs after a recent infection or continuous exposure to an allergy trigger.
  • Gastro-esophageal reflux (GERD): This digestive disorder occurs when stomach acid frequently backs up into the esophagus, causing heartburn. When the acid rises into the throat it can also cause a dry cough.

Types of Cough

There are many different types of coughs with distinct characteristics that can help your doctor identify what underlying issue may be causing it. If a cough brings up phlegm or mucus it is called a productive cough and could suggest pneumonia, bronchitis or the flu. The color of the mucus can signal a more serious problem. You should see a doctor if your cough brings up yellowish-green phlegm or blood. A cough that doesn’t produce mucus is called a dry or nonproductive cough.

Acute cough is the least serious type of cough. It only lasts for three weeks or less and will most likely clear up on its own. This type of cough will not need medical attention. However, if the cough is accompanied by other symptoms such as fever, headache, drowsiness or shortness of breath it should be brought to a doctor’s attention. Coughs that make certain sounds, like whooping, wheezing or barking, may also signal a bigger problem.

Chronic coughs last longer than eight weeks and can be the sign of a more serious or chronic lung disease. Learn more about possible causes.

Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.

Page last updated: March 3, 2020

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