Causes and Risk Factors of Wheezing

Wheezing—a high-pitched, whistle-like sound made when you breathe—is the result of air moving through narrowed airways. Asthma is the most common reason this occurs, but it's not the only possible cause. Wheezing could be a sign of numerous conditions, from minor issues (like breathing in cold air) to some extremely serious ones (such as COPD or a severe allergic reaction).

The most important thing to keep in mind is that wheezing is never normal. If you notice it when you inhale or exhale, and particularly if it persists or worsens, you should consult a doctor to find out what is restricting your airway.

Common Causes of Wheezing

Brianna Gilmartin / Verywell

Common Causes

Narrowing of the airways (also referred to as a blockage or obstruction) usually occurs in the small bronchial tubes. In some cases, it may be caused by problems with the larger airways (including the trachea or bronchi) or the vocal cords.

In either instance, the breath does not easily move in and out of the lungs. As air is forced through obstructed pathways, the whistling sound characteristic of wheezing occurs.

A number of issues can create an obstruction in the airways. Three of the most common are asthma, COPD, and vocal cord dysfunction.


Most wheezing is related to bronchial asthma and typically occurs in what is called the "yellow zone" of the disease (the middle range, when it is getting worse but before it becomes a serious medical issue). At that point, wheezing is often accompanied by other typical symptoms of asthma, including:

There are many different types of asthma, and many different ways for this chronic lung disease to manifest. But studies show that more than 53% of those who have symptoms consistent with any type of asthma have a history of wheezing.

Asthma can be well controlled with proper care. In the case of childhood asthma, children tend to "grow out of it." Symptoms cease with no lingering effects.

Chronic Obstructive Pulmonary Disease (COPD)

COPD is a progressive inflammatory disease in which the lungs become increasingly inflamed. This leads to symptoms such as a persistent cough, excessive phlegm, tightness in the chest, shortness of breath, and wheezing.

These symptoms may not be noticeable in the early stages of COPD, but they become more severe as the disease progresses.

There is no cure for the irreversible damage to the lungs. While COPD symptoms can be managed, the disease will continue to progress and become more debilitating with time.

Vocal Cord Dysfunction

Also called paradoxical vocal fold motion, vocal cord dysfunction (VCD) is characterized by wheezing caused by an abnormal closure of the vocal cords. Other symptoms may include shortness of breath and chest or neck tightness.

VCD's symptoms are so similar to asthma that it is sometimes called vocal cord asthma.

While the causes of VCD are still not completely clear, it seems to be related to postnasal drip, complications of asthma, and laryngopharyngeal reflux (in which stomach acid travels up the esophagus and irritates the larynx). Psychological factors are also thought to play a role in VCD in some patients.

VCD can be treated with speech therapy or breathing exercises, or by treating underlying causes such as reflux, allowing wheezing and other symptoms to go away.

After the World Trade Center attacks in 2001, there was an increased incidence of VCD among 9/11 first responders, which is believed to have been a result of the workers inhaling dust and chemicals at Ground Zero.

Less Common Causes

Various types of infections, allergic reactions, and other health concerns can all cause pulmonary obstructions that result in wheezing. Among these less common causes of wheezing are:

  • Structural abnormalities. This includes enlarged tonsils or adenoids that, when infected, can obstruct breathing in children. In studies, 36% of children with chronic wheezing had some kind of structural abnormality. Anatomic problems might also include a lung cyst or tumor.
  • Bronchospasm. This is a sudden narrowing of the airways common in asthma that can also be caused by other illnesses, exercise, a sudden intake of cold air, exposure to smoke, anesthesia, and other circumstances.
  • Allergies. Wheezing that occurs after eating certain foods, being bitten by an insect, or having been exposed to another allergen is the sign of an allergic reaction. Anaphylaxis is a severe allergic reaction that can lead to the sudden onset of wheezing. It's a potentially life-threatening emergency that requires immediate treatment.
  • Foreign body. Choking hazards such as coins, beads, or small candy can be lodged in in the trachea and cause wheezing.
  • Parainfluenza. Unrelated to the seasonal flu, parainfluenza actually refers to a group of viruses that cause upper- and lower-respiratory infections. Some of these result in wheezing, including bronchitis, bronchiolitis, and pneumonia.
  • Cystic fibrosis. Cystic fibrosis is a congenital disease that results in poor growth in childhood, weight problems, cough, and shortness of breath. Approximately 61% of children with cystic fibrosis experience wheezing associated with underlying respiratory problems in the first six years of life.
  • Gastroesophageal reflux disease (GERD). While GERD can be a cause of worsening asthma, GERD can also lead to recurrent pneumonia or scarring of the lungs—less common causes of wheezing.
  • Pulmonary embolism. A pulmonary embolism is a blood clot in the lungs. Wheezing may be one of several symptoms, but patients more commonly have acute shortness of breath and chest pain.

Is It Really Wheezing?

Nasal congestion can result in a sound that mimics a wheeze but isn't. And some children's diseases (such as croup) result in stridor, which some confuse with wheezing. Stridor is distinct and often described as the sound a seal makes.

Genetic Disorders and Birth Defects

Wheezing is related to a variety of complicated disorders. Some of these have genetic components, and you may be at greater risk if you have a chromosomal mutation.

AAT Deficiency

A genetic disorder called alpha-1-antitrypsin (AAT) deficiency causes lung damage that leads to COPD and emphysema. In this inherited condition, the body doesn't make enough of the protein AAT, which normally would stop a powerful enzyme that destroys dead cells in the lungs.

Without enough AAT, the enzyme starts destroying healthy cells, and the small air sacs in the lungs (alveoli) are damaged.

The earliest symptoms of AAT deficiency, which usually manifests between ages 20 and 50, include shortness of breath, reduced ability to exercise, and wheezing.

CFTR Mutation

Cystic fibrosis is one of the more common genetic diseases. Frequency varies by ethnic background, affecting one in 2,500 to 3,500 white newborns, but only one in 17,000 African Americans and one in 31,000 Asian Americans.

CF is an autosomal recessive disorder, meaning that you need to inherit the CFTR mutation from both your mother and father to have the disease. If you only inherit one defective gene, you won't have CF but will instead be a carrier of the mutated gene, meaning you can pass it on to offspring.

Tracheoesophageal Fistula

A very rare, non-inherited birth defect, tracheoesophageal fistula is a structural problem that causes wheezing. Babies with this condition are born with abnormal connections between the esophagus (the tube that leads from the throat to the stomach) and the trachea (the tube that leads from the throat to the windpipe and lungs).


Wheezing can also be due to a buildup of fluid in the lungs, which results from congestive heart failure (CHF).

With CHF, the heart cannot adequately pump blood through the body. The blood that can't get pushed forward backs up in the veins, and fluid leaks into the lungs.

Along with the wheezing, you may have a persistent cough that produces blood-tinged mucus.

Lifestyle Risk Factors

Some causes of wheezing cannot be controlled. However, there are several modifiable factors that can lower your risk for conditions that cause breathing difficulty. These include:

  • Cigarette smoking
  • Exposure to secondhand smoke
  • Exposure to chemicals
  • Indoor and outdoor air pollution

Sometimes spontaneous wheezing and other breathing problems brought on by these factors pass once the irritant is removed.

In other cases, these factors can cause serious illnesses, such as cancerous tumors or COPD that require treatment.

A Word From Verywell

Because wheezing is never part of normal breathing, you should always seek medical advice if you start to develop a wheeze and don't have a clear understanding of its cause, or if an existing wheeze is becoming more pronounced and frequent.

14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Pat Bass, MD
Dr. Bass is a board-certified internist, pediatrician, and a Fellow of the American Academy of Pediatrics and the American College of Physicians.