Croup is a common upper airway infection defined by swelling around the voice box (larynx) and windpipe (trachea). This inflammation produces the condition’s most recognizable symptom: a harsh, seal-like barking cough. The decision to send a child to school is determined by the severity of their symptoms and their potential to infect classmates, requiring clear guidance to balance health and disease prevention.
What Causes Croup and Why It Is Contagious
Croup is overwhelmingly caused by a viral infection, most frequently the human parainfluenza virus. Other respiratory viruses, such as Respiratory Syncytial Virus (RSV) or influenza, can also trigger the inflammation. The infection spreads person-to-person primarily through respiratory droplets released when an infected individual coughs or sneezes.
The viruses are also transmitted by touching contaminated surfaces or objects soiled with respiratory secretions. Young children, typically those between six months and five years old, are most susceptible because their airways are naturally narrower, making them prone to obstruction when swelling occurs. An infected person can spread the virus for up to a week before symptoms begin. The contagious period lasts until the fever and acute respiratory symptoms have resolved.
Symptom Criteria for School Exclusion
A child must be kept home from school immediately if they are running a fever, regardless of the cough’s appearance. The generally accepted standard for exclusion is a temperature of 100.4°F (38°C) or higher. The child must be fever-free for a full 24 hours without the assistance of any fever-reducing medication, such as acetaminophen or ibuprofen, before they can return to the classroom.
If the fever criteria are met, the child should still be excluded if the barking cough is frequent, uncontrolled, or severe. Any sign of difficulty breathing, such as rapid breathing, sucking in of the skin between the ribs, or flared nostrils, requires immediate exclusion and medical evaluation. A child should also remain home if they are generally unwell, lethargic, or unable to participate comfortably in regular school activities.
Home Management and Return to School Guidelines
Management of mild croup focuses on supporting the child and minimizing airway irritation while the virus runs its course. Parents should encourage the child to drink cool fluids frequently to help soothe the throat and maintain hydration. Giving an age-appropriate dose of an antipyretic medication can help manage any discomfort or fever.
Keeping the child calm is important, as crying or agitation can worsen the airway swelling and lead to increased respiratory effort. Some parents find that stepping outside into the cool, fresh air briefly or using a cool-mist humidifier helps to reduce the airway inflammation. However, the use of steam from a hot shower is no longer widely recommended due to the lack of proven effectiveness and the risk of accidental burns.
When to Seek Emergency Care
The child should be taken to a healthcare provider or the emergency room if severe symptoms develop. These include noisy breathing (stridor) that occurs even when the child is at rest, paleness, severe distress, or blueness around the lips.
Return to School Criteria
For a return to school, the child must have met the 24-hour fever-free threshold and show marked improvement in their cough and breathing. The child should appear well-rested, have a normal appetite, and possess the energy levels necessary to fully engage in the school environment.