Medically Reviewed By William C. Lloyd III, MD, FACS

What is a cough?

A cough is your body’s defensive reflex that functions to keep your airways clear of irritating or obstructing substances so that you can breathe effectively. A cough can be dry or it can be productive, meaning that you are coughing up mucus (also known as phlegm or sputum). A cough is one of the most common reasons why people visit their primary care doctor.

A cough is a symptom of a wide variety of mild to serious diseases, disorders and conditions. A cough can result from infection, inflammation, trauma, malignancy, airway obstruction, and other abnormal processes.

You may cough after inhaling an irritant, such as dust, smoke, or pollen. A cough may also be the result of a disorder or disease, such as influenza, upper respiratory infection, or allergies. A cough can accompany serious and potentially life-threatening conditions as well, including pneumonia, acute bronchitis, bronchiolitis, asthma, malignancy, and congestive heart failure.

Depending on the cause, a cough can begin suddenly and disappear quickly, such as after inhaling secondhand smoke. An acute cough that comes on suddenly and lasts up to two to three weeks can be caused by the common cold or other respiratory infection; whereas, a chronic cough over a long period of time (lasting more than eight weeks) may be caused by gastroesophageal reflux disease, asthma, or smoking.

A cough can be a sign of a very serious or life-threatening disorder. If you have difficulty breathing, chest pain, rapid heartbeat, swollen legs or ankles, or are coughing up pink, frothy mucus, seek immediate medical care (911). The latter is a sign of pulmonary edema and can lead to respiratory arrest. Any sign of blood is a potentially serious problem. Seek prompt medical care if your cough is persistent, recurrent, or causes you concern.

What other symptoms might occur with a cough?

A cough often occurs in conjunction with other symptoms, which vary depending on the underlying disease, disorder or condition. Other symptoms include fever, shortness of breath, and chest pain. Some symptoms, such as sounds the lungs make while you’re breathing, changes in blood pressure, and low blood oxygen levels may only be evident using certain instruments in the doctor’s office or hospital.

Common symptoms may occur along with cough

Cough may occur with other symptoms including:

  • Coughing up clear, yellow, light brown, or green mucus
  • Fever
  • Sore throat
  • Vomiting

Other symptoms may occur along with cough

Cough may occur with other less common symptoms including:

  • Diarrhea
  • Fatigue

Serious symptoms that might indicate a life-threatening condition

In some cases, a cough may occur with other symptoms and certain combinations of symptoms that might indicate a serious or life-threatening condition that should be evaluated immediately in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of the following symptoms:

  • Coughing up pink, frothy mucus
  • Difficulty speaking
  • Severe pain upon swallowing
  • Very painful cough or pain while breathing deeply

What causes a cough?

A cough has many causes, the most common of which is an upper airway infection, such as a common cold. A persistent cough can be due to whooping cough (pertussis) or a sign of a chronic lung condition, such as emphysema or asthma. Some individuals taking angiotensin-converting enzyme inhibitors (ACE inhibitors) experience a persistent dry cough, which ceases with drug discontinuation. Whooping cough is uncommon in infants due to vaccination, but it is surprisingly common in adults because the vaccination becomes less effective over time.

Very serious and life-threatening conditions that cause coughing include congestive heart failure, pulmonary edema, and lung cancer. Other possible causes include allergies, pneumonia, and bronchitis. Because there are so many different possibilities, some of which are life threatening, it is important to contact your doctor to discuss your symptoms and answer your questions.

Infectious causes of cough

Cough is a symptom of various viral and bacterial infections including:

  • Acute bronchitis
  • Common cold (viral respiratory infection)
  • Croup (viral illness that is common in young children)
  • Influenza (flu)
  • Pneumonia
  • Tuberculosis (serious infection affecting the lungs and other organs)
  • Whooping cough (pertussis)

Other causes of cough

Other causes of cough include:

  • Acid reflux or gastroesophageal reflux disease (GERD)
  • Airway irritation such as from air pollution
  • Asthma and allergies
  • Chronic obstructive pulmonary disease (COPD, includes emphysema and chronic bronchitis)
  • Congestive heart failure (deterioration of the heart’s ability to pump blood)
  • Foreign body (airway obstruction)
  • Lung cancer
  • Postinfectious cough

Medications can cause a cough

Certain medications that can cause a cough include ACE inhibitors (including captopril), which is used to control high blood pressure.

Questions for diagnosing the cause of a cough

To aid in diagnosing the cause of your cough, your doctor or licensed health care practitioner will ask you questions related to your symptoms including:

  • How long have you had the cough?
  • Are you coughing up anything (including blood)?
  • Are you breathing through your mouth (instead of your nose)?
  • Is your cough keeping you up at night?
  • Do you have a fever?

What are the potential complications of a cough?

A cough can be a sign of an infectious or inflammatory process, many of which can be easily treated. It is important to contact your health care provider when you experience a cough without an obvious cause or if your cough is persistent, recurrent, or causes you concern. Once the underlying cause is diagnosed, following the treatment you and your doctor design specifically for you can help lower your risk of potential complications including:

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  1. Cough.
  2. Cough. Medline Plus, a service of the National Library of Medicine National Institutes of Health.
  3. Tierney LM Jr., Saint S, Whooley MA (Eds.) Current Essentials of Medicine (4th ed.). New York: McGraw-Hill, 2011.
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 10
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.