Croup is breathing difficulty accompanied by a "barking" cough. Croup, which is swelling around the vocal cords, is common in infants and children and can have a variety of causes.

Viral croup is the most common. Other possible causes include bacteria, allergies, and inhaled irritants. Acid reflux from the stomach can trigger croup.

Croup is usually (75 percent of the time) caused by parainfluenza viruses, but RSV, measles, adenovirus, and influenza can all cause croup.

Before the era of immunizations and antibiotics, croup was a dreaded and deadly disease, usually caused by the diphtheria bacteria. Today, most cases of croup are mild. Nevertheless, it can still be dangerous.

Croup tends to appear in children between 3 months and 5 years old, but it can happen at any age. Some children are prone to croup and may get it several times.

In the Northern hemisphere, it is most common between October and March, but can occur at any time of the year.

In severe cases of croup, there may also be a bacterial super-infection of the upper airway. This condition is called bacterial tracheitis and requires hospitalization and intravenous antibiotics. If the epiglottis becomes infected, the entire windpipe can swell shut, a potentially fatal condition called epiglottitis.

Croup features a cough that sounds like a seal barking. Most children have what appears to be a mild cold for several days before the barking cough becomes evident. As the cough gets more frequent, the child may have labored breathing or stridor (a harsh, crowing noise made during inspiration).

Croup is typically much worse at night. It often lasts 5 or 6 nights, but the first night or two are usually the most severe. Rarely, croup can last for weeks. Croup that lasts longer than a week or recurs frequently should be discussed with your doctor to determine the cause.

Children with croup are usually diagnosed based on the parent's description of the symptoms and a physical exam. Sometimes a doctor will even identify croup by listening to a child cough over the phone. Occasionally other studies, such as x-rays, are needed.

A physical examination may show chest retractions with breathing. Listening to the chest through a stethoscope may reveal prolonged inspiration or expiration, wheezing, and decreased breath sounds.

An examination of the throat may reveal a red epiglottis. A neck x-ray may reveal a foreign object or narrowing of the trachea.

Most cases of croup can be safely managed at home, but call your health care provider for guidance, even in the middle of the night.

Cool or moist air can bring relief. You might first try bringing the child into a steamy bathroom or outside into the cool night air. If you have a cool air vaporizer, set it up in the child's bedroom and use it for the next few nights.

Acetaminophen can make the child more comfortable and lower a fever, lessening his or her breathing needs. Avoid cough medicines unless you discuss them with your doctor first.

You may want your child to be seen. Steroid medicines can be very effective at promptly relieving the symptoms of croup. Medicated aerosol treatments, if necessary, are also powerful.

Serious illness requires hospitalization. Increasing or persistent breathing difficulty, fatigue, bluish coloration of the skin, or dehydration indicates the need for medical attention or hospitalization.

Medications are used to help reduce upper airway swelling. This may include aerosolized racemic epinephrine, corticosteroids taken by mouth, such as dexamethasone and prednisone, and inhaled or injected forms of other corticosteroids. Oxygen and humidity may be provided in an oxygen tent placed over a crib. A bacterial infection requires antibiotic therapy.

Increasing obstruction of the airway requires intubation (placing a tube through the nose or mouth through the larynx into the main air passage to the lungs). Intravenous fluids are given for dehydration. In some cases, corticosteroids are prescribed.

Viral croup usually goes away in 3 to 7 days. The outlook for bacterial croup is good with prompt treatment.

If an airway obstruction is not treated promptly, respiratory distress (severe difficulty breathing) and respiratory arrest can occur.

• Respiratory distress
• Respiratory arrest
• Epiglottitis
• Bacterial tracheitis
• Atelectasis (collapse of part of the lung)
• Dehydration

Most croup can be safely managed at home with telephone support from your health care provider. Call 911 if:

• The croup is possibly being caused by an insect sting or inhaled object
• The child has bluish lips or skin color
• The child is drooling
• The child is having trouble swallowing

Depending on the severity of the symptoms, call 911 or your health care provider for any of the following:

• Stridor (noise when breathing in)
• Retractions (tugging-in between the ribs when breathing in)
• Struggling to breathe
• Agitation or extreme irritability
• Not responding to home treatment

Wash your hands frequently and avoid close contact with those who have a respiratory infection.

The diphtheria, Haemophilus influenzae (Hib), and measles vaccines protect children from some of the most dangerous forms of croup.

Long, SS. Croup (viral laryngotracheobronchitis). In: Principles and Practice of Pediatric Infectious Diseases. 2nd ed. Elsevier, 2003; 210-211.

Treanor JJ, Hayden FG. Viral Infections. In: Mason RJ, Murray JF, Broaddus VC, Nadel JA. Mason: Murray & Nadel's Textbook of Respiratory Medicine. 4th ed. Philadelphia, Pa: Saunders Elsevier; 2005: chap 31.

Knutson D. Viral croup. Am Fam Physician. 2004; 69(3): 535-40.

Roosevelt GE. Acute Inflammatory Upper Airway Obstruction (Croup, Epiglottitis, Laryngitis, and Bacterial Tracheitis). In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF. Kliegman: Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 382.