Croup is a common respiratory illness that primarily affects infants and young children. It involves inflammation of the voice box (larynx) and windpipe (trachea), resulting in breathing difficulties and distinctive symptoms such as a cough that sounds like a seal barking.

Croup is most common between the ages of 3 months and 5 years, and symptoms are usually the most severe in patients under 3 years old. It occurs more often in boys than girls. Croup can occur year round, but is more common in colder weather. Children who are born prematurely or who have a history of respiratory problems may be more susceptible to croup or a recurrence of croup.

Most cases of croup are caused by a viral infection, according to the American Academy of Family Physicians. Croup is less commonly caused by bacteria, allergies, inhaled irritants or acid reflux. Symptoms may be worse at night, but are generally mild and go away on their own.

The usual course of treatment of croup is therapy aimed at alleviating symptoms. At home, this includes inhaling moist air, such as from shower steam or a cool mist humidifier, or taking a child outside for cool air. Avoiding smoke, increasing fluids and keeping the child calm also helps.

Croup symptoms can be disconcerting for both parents and children. Parents may want to seek medical attention the first time a child displays symptoms, especially if they occur in the middle of the night. They may call their pediatrician’s on-call service or visit a hospital emergency room. When symptoms are severe or persist, parents should seek immediate medical attention for their child. An evaluation may include a description of the child’s symptoms and a physical examination. A physician may be able to identify croup by listening to a child cough over the phone. Certain medications may be prescribed to alleviate the child’s symptoms. In rare cases, children with croup may need to be hospitalized. This may be done for observation, or when symptoms indicate significant breathing problems or dehydration.

Most cases of croup are contagious. Croup can be prevented by practicing good hygiene (e.g., frequent handwashing). There is currently no vaccine available that prevents most cases of croup, although several existing vaccines for other conditions can protect children against the most severe cases of croup.