Stridor is a gasping sound during inhalation resulting from a partial blockage of the throat (pharynx), voice box (larynx), or windpipe (trachea).

Stridor is usually loud enough to be heard at some distance. The sound is caused by turbulent airflow through a narrowed upper airway. In children, the cause may be croup, an inhaled foreign object, or, rarely, an infection of the epiglottis. In adults, the cause may be a tumor, an abscess, swelling (edema) in the upper airway, or a malfunction of the vocal cords.

Stridor that causes shortness of breath when the person is at rest is a medical emergency. In such cases, a tube may be inserted through the person's mouth or nose (tracheal intubation) or through a small surgical incision directly into the trachea (tracheostomy) to allow air to get past the blockage and prevent suffocation. The cause usually becomes clear during tracheal intubation, when the doctor can see the upper airway directly. If tracheal intubation is not done, the diagnosis is usually determined by inserting a flexible viewing tube through the nose and upper airway (a procedure called nasopharyngeal laryngoscopy).

Last full review/revision July 2012 by Noah Lechtzin, MD, MHS