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Medical Author:

John Mersch, MD, FAAP

John Mersch, MD, FAAP

Dr. Mersch received his Bachelor of Arts degree from the University of California, San Diego, and prior to entering the University Of Southern California School Of Medicine, was a graduate student (attaining PhD candidate status) in Experimental Pathology at USC. He attended internship and residency at Children's Hospital Los Angeles.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• Croup facts
• What is croup? What causes croup?
• Is croup contagious?
• What are croup symptoms?
• What is the treatment for croup?
• What warning signs should parents look for with croup?
• Patient Comments: Croup - Treatments
• Patient Comments: Croup - Symptoms
• Find a local Pediatrician in your town
• Croup Index

Croup is contagious and is usually spread by airborne infectious droplets sneezed or coughed by infected children. When a healthy child inhales infectious droplets, symptoms can develop in two to three days. The infection can also be spread by infected mucus deposited on doors, furniture, toys, and other objects. A healthy child can become infected by accidentally touching the infectious mucus and transferring the infection into his/her mouth.

Viral croup may have two distinct presentations both of which are a consequence of swelling of the vocal cords and therefore narrowing of the airway. The more common variety causes symptoms of fever (100 F-103 F), mild hoarseness, and sore throat two to three days after virus exposure. The characteristic dry "barking seal" cough is soon to follow. The barking cough may be associated with a harsh, raspy sound during inspiration. (This sound, called "stridor," has been noted to resemble the breathing of the Star Wars character Darth Vader.) The symptoms commonly last for four to seven days.

A less frequent form of croup is called "acute spasmodic croup." Children with this form of croup will appear totally well when put to bed at night only to awaken their parents in the middle of the night with the above described barky cough and stridor. Fever and sore throat are not noted in these children, and the symptoms completely resolve within eight to 10 hours from onset. The child then appears totally well until this same acute onset recurs the following night. This on/off pattern may occur over three to four nights in a row and then transition into symptoms similar to the common cold -- mucoid nasal discharge and a "wet" cough for several days.

These two different forms of croup are the result of which particular virus has infected the child. Manifestations of croup may vary from mild (common) to life-threatening (rare). The severity of symptoms is proportional to the amount of relative narrowing of the breathing airway. The more severe the vocal cord narrowing the more effort is required to inhale. A severely sick child will refuse to lie down and demand to remain in an upright position. They will show retractions of the skin above the collarbone and between the ribs with inspiration and may develop facial blueness (cyanosis). Apparent exhaustion and decreased respiratory effort are indicators of impending respiratory failure and are cause for immediate paramedic evaluation and transport to the emergency department of the closest hospital.