Wheezing: Causes and When It Needs a Doctor

What wheezing sounds like and why it happens

A wheeze is a continuous, musical or whistling sound. It is made when air passes quickly through a narrowed small airway, which makes the airway wall vibrate. You hear it most when breathing out, because airways naturally narrow slightly as you exhale.

Airways narrow because of:

• muscle tightening around the airway (bronchospasm), as in asthma
• swelling of the airway lining from inflammation or infection
• mucus partly blocking the airway
• something pressing on or blocking the airway, such as a tumor or a swallowed object

Wheezing vs stridor and snoring sounds

A harsh, high-pitched sound on breathing in is called stridor. It comes from narrowing of the throat, voice box or windpipe, as in croup, epiglottitis or anaphylaxis, and is often more dangerous. A rattling or snore-like sound during a cold usually comes from mucus in the nose or throat, not the lungs.

What causes wheezing

Common causes

Less common causes

• Pneumonia: fever, cough with phlegm, chest pain on breathing, feeling very unwell.
• Heart failure ("cardiac asthma"): fluid in the lungs causes wheeze, breathlessness lying flat, waking breathless at night and swollen ankles.
• Acid reflux: stomach acid reaching the throat can trigger wheeze and cough, especially at night.
• Inhaled foreign object: sudden wheeze or cough in a young child, often on one side only.
• Vocal cord dysfunction: the vocal cords close when you breathe in, mimicking asthma but not responding to inhalers.
• Bronchiectasis: permanently widened airways with daily large amounts of phlegm and repeated infections.
• Medicines: beta-blockers and, in some people with asthma, aspirin or NSAIDs.
• Tumors pressing on an airway, causing a fixed wheeze in one area, often with weight loss or coughing blood.

Sudden wheezing during flu or a cold

Viral infections inflame the airways and are the most common trigger of asthma attacks. If you suddenly start wheezing during the flu, it may be a flare of known or previously undiagnosed asthma, bronchitis, or less often pneumonia. See a doctor if you are breathless, the wheeze is getting worse, or you have a high fever.

Emergency signs: blue lips, unable to speak

These signs mean the body is not getting enough oxygen. Call 911 or your local emergency number:

• lips, tongue or fingertips turning blue or gray (cyanosis)
• unable to finish a sentence in one breath
• skin pulling in between or under the ribs, or at the base of the neck
• nostrils flaring, or head bobbing in babies
• breathing very fast, or slowing down from exhaustion
• a "silent chest": wheezing that stops while breathing is still hard. This means very little air is moving
• agitation, panic, confusion or drowsiness

While you wait, sit upright, stay as calm as possible, and use a reliever inhaler as directed in your asthma action plan, or an epinephrine auto-injector for anaphylaxis.

How doctors diagnose the cause

The doctor will ask when the wheezing started, whether it comes and goes, triggers, smoking, allergies, family history and other symptoms. They will listen to your chest and measure your oxygen level with a finger clip (pulse oximetry). Tests depend on the clues:

• Peak flow or spirometry: measures how fast you can blow out, and whether an inhaler improves it. This is key for diagnosing asthma and COPD.
• FeNO test: measures airway inflammation in suspected asthma.
• Chest X-ray: for pneumonia, heart failure, a foreign object or a tumor.
• Blood tests: including eosinophil count and allergy tests.
• CT scan or bronchoscopy: for a wheeze in one place or a suspected blockage.

Treatment for wheezing

Treatment is aimed at the cause:

• Bronchodilator inhalers (such as albuterol) relax airway muscles within minutes. A spacer helps the medicine reach the lungs, especially for children.
• Inhaled steroids reduce airway inflammation and prevent attacks in asthma.
• Oral steroids for a few days settle a severe flare of asthma or COPD.
• Antibiotics only if a bacterial infection such as pneumonia is found.
• Epinephrine for anaphylaxis.
• Diuretics for heart failure, and acid suppression for reflux.
• Oxygen and supportive care in hospital for severe attacks or bronchiolitis in babies.

At home

• Avoid smoke, including secondhand smoke and vaping.
• Avoid known triggers such as pollen, pet dander, dust mites and cold air.
• Keep your reliever inhaler with you and follow a written asthma action plan.
• Breathe warm, moist air, such as in a steamy bathroom, which may ease a mild wheeze from a cold.
• Get flu, COVID-19 and pneumococcal vaccines as recommended, especially with asthma or COPD.

Frequently asked questions

When does wheezing need a doctor's attention?

Any first episode of wheezing should be checked by a doctor. Get emergency help if wheezing comes with blue or gray lips, difficulty speaking, ribs sucking in, confusion, or swelling of the face or throat. Also see a doctor if wheezing keeps returning or does not settle with your usual inhaler.

What causes wheezing with blue lips and being unable to speak?

This combination means the airways are so narrowed that not enough oxygen reaches the blood. The usual causes are a severe asthma attack, anaphylaxis, a severe COPD flare or an inhaled object. It is an emergency: call 911 or your local emergency number right away.

Is wheezing always asthma?

No. Asthma is the most common cause, but wheezing can come from COPD, chest infections, bronchiolitis in babies, allergic reactions, heart failure, reflux, inhaled objects or, rarely, tumors. A doctor can tell them apart with an examination and breathing tests.

Why do I wheeze at night?

Night-time wheezing is typical of asthma, because airway inflammation peaks in the early hours. It can also be caused by acid reflux when lying down, dust mites in bedding, or heart failure. Waking breathless at night is worth discussing with your doctor.

Can a cold cause wheezing in adults?

Yes. Viral infections inflame the airways and can cause wheeze for a few weeks, especially in people who smoke or have asthma. If it lasts more than 3 weeks, keeps returning, or comes with breathlessness or fever, see a doctor.