Difference Between Stridor and Wheezing

Key Difference – Stridor vs Wheezing

The key difference between Stridor and Wheezing is that Stridor is the harsh sound generated during inspiration, in a patient with a larger airway obstruction while Wheezing is the polyphonic musical sounds generated during expiration, in a patient with bronchospasms. Therefore, these two sounds basically indicate an obstruction in the respiratory passage at different levels. In the respiratory passage, the airway starts from the larynx and descends  into the thorax and  the trachea. At Carina, the trachea divides into right and left main bronchi. Bronchi are further subdivided into smaller airways in a cascade-like manner.

What is Stridor?

Stridor or the harsh monophonic sound occurring in larger airway obstructions is a red flag sign of impending complete airway obstruction. Stridor typically occurs during inspiration. Larger airways include trachea and bronchi. Obstructions to these tubes can occur due to multiple causes such as foreign body inhalation, severe mucosal edema, external compression of the airways, toxic gasses, allergic reactions, etc. Sometimes, stridor can be very loud and may be audible without the stethoscope. However, it can be better listened to, by using the stethoscope. If a patient has got stridor, it indicates that urgent intervention is needed to protect the airway from impending complete obstruction. Therefore, urgent hospitalization, imaging, and intervention are required. If it caused by a foreign body urgent removal of the foreign body by bronchoscopy is indicated. Sometimes if the cause is not reversible immediately, temporary insertion of an endotracheal tube is required. These patients can get completely respiratory obstruction and death in few minutes. Therefore, they should be managed by experienced people in the health care team very carefully.

Key Difference - Stridor vs Wheezing


What is Wheezing?

Wheezing is a common clinical sign which occurs in multiple smaller airway obstructions such as in bronchospasms. This is a cardinal sign in Asthma. The wheezing sound is generated by the passage of air through multiple narrowed airways during expiration. It causes trapping of air proximal to the narrowing and therefore chest tightness. Wheezing is a common occurring in the childhood especially among the children with atopic or allergic tendencies. Bronchospasms are caused by smooth muscle contraction as well as from mucosal edema and accumulation of secretions in the airways. Wheezing can be treated with bronchodilator medications such as salbutamol (beta agonists). Steroids are used as the preventive medication for recurrent bronchospasms. Specially bronchodilators can be delivered by nebulization and via inhalers. When the bronchospasms are severe more intense and urgent treatment is indicated.

Difference Between Stridor and Wheezing

Airways narrowed as a result of the inflammatory response cause wheezing.

What is the difference between Stridor and Wheezing?

Definition of Stridor and Wheezing

Stridor: Stridor is a term used to describe noisy breathing in general, and to refer specifically to a high-pitched crowing sound associated with croup, respiratory infection, and airway obstruction.

Wheezing: Wheezing is a high-pitched whistling sound associated with labored breathing.

Characteristics of Stridor and Wheezing


Stridor: Stridor occurs due to obstruction of larger airways.

Wheezing: Wheezing occurs due to obstruction of the smaller airways.


Stridor: Stridor is a harsh monophonic sound.

Wheezing: Wheezing is a musical polyphonic sound.

Timing in relation to the respiratory cycle

Stridor:Stridor occurs during inspiration.

Wheezing: Wheezing occurs during expiration.

Common causes

Stridor: Stridor is commonly caused by foreign body inhalation.

Wheezing: Wheezing is the commonest symptom of Asthma.


Stridor: Stridor indicates a serious upper airway obstruction requiring urgent attention.

Wheezing: Wheezing can be different in severity based on the severity of the underlying bronchospasms.


Stridor: Stridor needs urgent protection of the upper airway.

Wheezing: Wheezing is treated with bronchodilators such as beta agonists.


Image Courtesy:

“Diagram showing a bronchoscopy CRUK 053″ by Cancer Research UK – Original email from CRUK. ( CC BY-SA 4.0) via Commons 
“Asthma before-after-en” by FDA/Renée Gordon; vectors by Mysid. – Vectorized in Inkscape by Mysid from (Public Domain) via Commons