MSD Manual

Please confirm that you are not located inside the Russian Federation

honeypot link



Rebecca Dezube

, MD, MHS, Johns Hopkins University

Last full review/revision Feb 2020| Content last modified Feb 2020
Click here for the Professional Version
Topic Resources

Wheezing is a high-pitched, whistling sound that occurs during breathing when the airways are partially blocked. (See also Wheezing in Infants and Young Children.)

Causes of Wheezing

Wheezing results from a narrowing or partial blockage (obstruction) somewhere in the airways. The narrowing may be widespread (as occurs in asthma, chronic obstructive pulmonary disease [COPD], and some severe allergic reactions) or only in one area (as may result from a tumor or a foreign object lodged in an airway).

Common causes

Overall, the most common causes are

Less common causes

Wheezing may occur in other disorders that affect the small airways, including heart failure, a severe allergic reaction (anaphylaxis), and inhalation of a toxic substance. Wheezing caused by heart failure is called cardiac asthma.

Sometimes, otherwise healthy people wheeze during a bout of acute bronchitis. In children, wheezing may be caused by bronchiolitis (infection of the lower respiratory tract) or inhalation (aspiration) of a foreign object (see table Some Causes and Features of Wheezing).

Evaluation of Wheezing

A person with severe breathing problems (respiratory distress) is evaluated and treated at the same time.

The following information can help people decide when a doctor's evaluation is needed and help them know what to expect during the evaluation.

Warning signs

In people with wheezing, the following symptoms are of particular concern:

  • Labored breathing, weakening efforts to breathe, or a decreased level of consciousness

  • Swelling of the face and tongue

When to see a doctor

People with warning signs or shortness of breath should go to the hospital emergency department immediately, by ambulance if necessary. People who have wheezing that comes and goes and are not short of breath can usually wait a day or two.

What the doctor does

Doctors first ask questions about the person's symptoms and medical history and then do a physical examination. What doctors find during the history and physical examination often suggests a cause and the tests that may need to be done (see table Some Causes and Features of Wheezing).

Doctors determine whether the wheezing is occurring for the first time or has occurred before. If the person has had wheezing before, they determine whether current symptoms are different in nature or severity.

Important clues to a diagnosis are

  • Whether the wheezing started suddenly or gradually

  • Whether it comes and goes

  • Whether any conditions (such as an upper respiratory infection, exposure to an allergen, particular seasons of the year, cold air, exercise, or feeding in infants) trigger it or make it worse

Other symptoms that can provide clues to the diagnosis include shortness of breath, fever, cough, and sputum production. Doctors ask about the person's history of smoking and exposure to secondhand smoke.

During the physical examination, doctors check the person's temperature and heart and breathing rates. Doctors look for signs of respiratory distress and examine the lungs, particularly how well air moves in and out and whether wheezing seems to affect all of the lungs or only part. A doctor is usually able to detect wheezing by listening with a stethoscope as the person breathes. Loud wheezing can be heard easily, sometimes even without a stethoscope. To hear mild wheezing, doctors may need to listen with a stethoscope while the person exhales forcefully. A persistent wheeze that occurs in one location in smokers may be due to lung cancer. Doctors also examine the heart, nose and throat, limbs, hands, feet, and skin.


Some Causes and Features of Wheezing


Common Features*



Sometimes symptoms of an upper respiratory infection (such as a stuffy nose)

Usually no known history of a lung disorder

A doctor's examination

Wheezing that starts suddenly, usually within 30 minutes of exposure to a known or potential allergen such as pollen

Often a stuffy nose, hives, itchy eyes, and sneezing

A doctor's examination

Usually a history of asthma

Wheezing that starts spontaneously or after exposure to specific stimuli (such as pollen or another allergen, an upper respiratory infection, cold, or exercise)

A doctor's examination

Sometimes one or more of the following tests:

  • Tests to evaluate how well the lungs are functioning (pulmonary function tests)

  • Measurement of peak air flow (how fast air can be exhaled)

  • Measurement of lung function before and after exercise or administration of methacholine (a drug that narrows airways)

  • Sometimes use of bronchodilators (drugs that widen airways) to see whether symptoms go away

Bronchiolitis (infection of the lower respiratory tract)

In children under 18 months old

Usually occurring from November to April in the Northern Hemisphere

Usually symptoms of an upper respiratory infection (such as a stuffy nose and fever) and rapid breathing

A doctor's examination

A COPD flare-up

In middle-aged or older people

In people who already have COPD

Usually a history of extensive smoking

Labored breathing

A chest x-ray

Drugs (such as ACE inhibitors, beta-blockers, aspirin, and other NSAIDs)

In people who have recently started using a new drug, most often in those with a history of airway obstruction (as occurs in asthma)

A doctor's examination

A foreign object that has been inhaled

High-pitched wheezing or cough that starts suddenly in people (typically infants or young children) without any symptoms of an upper respiratory infection, fever, or other symptoms of illness

A chest x-ray or CT of the chest

GERD with repeated reflux of stomach contents into the lungs (chronic aspiration)

Chronic or recurring wheezing

Often burning pain in the chest (heartburn) or abdomen that tends to worsen after eating certain foods, while exercising, or while lying flat

A sour taste, particularly after awakening


A cough that occurs in the middle of the night or early morning

No symptoms of an upper respiratory infection or allergy

Sometimes only a doctor's examination

Sometimes use of drugs that suppress acid, such as a histamine-2 (H2) blocker or proton pump inhibitor, to see whether symptoms go away

Sometimes insertion of a flexible viewing tube into the esophagus and stomach (endoscopy)

Sometimes placement of a sensor in the esophagus to monitor acidity (pH) for 24 hours

Usually swelling (edema) of the legs

Shortness of breath that worsens while lying flat or that appears 1–2 hours after falling asleep

Sounds suggesting fluid in the lungs, heard through a stethoscope

A chest x-ray

Sometimes a blood test to measure a substance that is produced when the heart is strained called brain natriuretic peptide (BNP)

Sometimes echocardiography

Irritants that are inhaled

Wheezing that starts suddenly after exposure to irritants at work (occupational exposure) or inappropriate use of cleaning products

A doctor's examination

Wheezing while inhaling and exhaling, especially in people with risk factors for or signs of cancer (such as a history of smoking, night sweats, weight loss, and coughing up blood)

A chest x-ray or CT of the chest

* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

† Doctors usually measure the oxygen level in blood with a sensor placed on a finger (pulse oximetry). A chest x-ray is usually taken unless the person's symptoms are clearly a flare-up of an already diagnosed chronic disorder.

ACE = angiotensin-converting enzyme; COPD = chronic obstructive pulmonary disease; CT = computed tomography; GERD = gastroesophageal reflux disease; NSAIDs = nonsteroidal anti-inflammatory drugs.


Tests are done to assess severity, determine diagnosis, and identify complications. They usually include the following:

  • Measurement of oxygen levels in the blood with a sensor placed on a finger (pulse oximetry)

  • A chest x-ray (if the diagnosis is unclear)

  • Sometimes measurement of gases (oxygen and carbon dioxide) and acidity (pH) in an artery (arterial blood gas analysis)

  • Sometimes tests to evaluate how well the lungs are functioning (pulmonary function testing)

If wheezing has occurred for the first time, a chest x-ray may help in the diagnosis. In people with persistent, repeated, or undiagnosed episodes of wheezing, pulmonary function tests may be needed to help measure the extent of airway narrowing and to assess the benefits of treatment. If asthma seems possible but is not confirmed by pulmonary function tests, people may be asked to exercise or be given a drug that triggers wheezing in people with asthma. If airway obstruction occurs, asthma can be confirmed.

If doctors suspect a tumor or a foreign object lodged in an airway, they can insert a flexible viewing tube (bronchoscope) into the airway to identify the problem and, if it is an object, remove it.

Treatment of Wheezing

The main goal of treatment is to treat the underlying disorder.

Bronchodilators (which widen the airways), such as inhaled albuterol, can relieve wheezing. Corticosteroids, taken by mouth for a week or two, can often help relieve an acute episode of wheezing if it is due to asthma or chronic obstructive pulmonary disease.

Long-term control of persistent wheezing due to asthma may require inhaled corticosteroids, mast cell stabilizers, leukotriene modifiers, or immunomodulators (drugs that affect the immune system—see table Drugs Commonly Used to Treat Asthma).

Antihistamines (such as diphenhydramine) given intravenously, corticosteroids (such as methylprednisolone), albuterol taken through a nebulizer, and epinephrine injected under the skin (subcutaneously) are given to people with a severe allergic reaction.

Key Points about Wheezing

  • Asthma is the most common cause, but not all wheezing is caused by asthma.

  • Wheezing that starts suddenly in people without a lung disorder may be due to inhalation of a foreign object or a toxic substance, an allergic reaction, or heart failure.

  • Pulmonary function tests can identify and measure airway narrowing.

  • Inhaled bronchodilators can help relieve wheezing, but the disorder causing wheezing must also be treated.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Test your knowledge

Asbestosis is widespread scarring of lung tissue caused by breathing asbestos dust. Which of the following is responsible for the largest number of lung cancer cases among people with asbestosis? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID