Wheezing is a high-pitched whistling sound made while breathing. It’s often associated with difficulty breathing. Wheezing may occur during breathing out (expiration) or breathing in (inspiration).

Causes

Inflammation and narrowing of the airway in any location, from your throat out into your lungs, can result in wheezing.

The most common causes of recurrent wheezing are asthma and chronic obstructive pulmonary disease (COPD), which both cause narrowing and spasms (bronchospasms) in the small airways of your lungs.

However, any inflammation in your throat or larger airways can cause wheezing. Common causes include infection, an allergic reaction or a physical obstruction, such as a tumor or a foreign object that’s been inhaled.

All of the following conditions can lead to wheezing:

Allergies
Anaphylaxis (a severe allergic reaction, such as to an insect bite or medication)
Asthma — a long-term condition that affects airways in the lungs.
Bronchiectasis (a chronic lung condition in which abnormal widening of bronchial tubes inhibits mucus clearing)
Bronchiolitis (especially in young children)
Bronchitis
Childhood asthma
COPD (chronic obstructive pulmonary disease) — the blanket term for a group of diseases that block airflow from the lungs — including emphysema.
Emphysema
Epiglottitis (swelling of the “lid” of your windpipe)
Foreign object inhaled: First aid
Gastroesophageal reflux disease (GERD)
Heart failure
Lung cancer
Medications (particularly aspirin)
Obstructive sleep apnea (a condition in which breathing stops and starts during sleep)
Pneumonia — an infection in one or both lungs.
Respiratory syncytial virus (RSV) — especially in young children
Respiratory tract infection (especially in children younger than 2)
Smoking
Vocal cord dysfunction (a condition that affects vocal cord movement)

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