Croup is a common infection of small children, usually younger than 5 years old. It’s caused by the parainfluenza virus, is very contagious (spread through coughing and sneezing), and has a short incubation period of 2-6 days (the time from exposure to symptoms).

Parainfluenza virus has a predilection for going right for the voice box (larynx), trachea, and upper bronchial tubes. In fact, another name for croup is acute laryngotracheobronchitis. The first symptoms of illness may be a mild runny nose followed by a mild dry cough. After a day or two, and often suddenly in the middle of the night, the larynx gets hit and the tissue just below the vocal cords — the narrowest part of the upper airway anatomically — begins to swell, causing the infant/toddler/child to develop a loud barking cough and hoarse voice. If the swelling gets severe enough, children will begin to have stridor — a sound made when a breath is taken in and usually a sign of significant airway narrowing caused by the swelling. Most children who are old enough to complain will say they have a sore throat, especially when they cough, but in actuality it is the area of the larynx (where the “Adam’s Apple” is) which hurts. If laryngeal swelling is severe enough, infants and children can have a very difficult time breathing, often necessitating an urgent office visit or a trip to the emergency room.

There are a few general facts about croup that parents should know:

  • Spring and Fall are the two main seasons for croup in the Northeast.
  • The worst symptoms of croup usually occur in the middle of the night when children (mostly infants and toddlers) wake up with a loud barky cough, noisy breathing (stridor), and sometimes difficulty breathing.
  • The second night of the illness is often worse than the first.
  • Most seem to improve during the day — croup is almost always worse at night.
  • Pediatricians often advise bringing a child into a steamy shower or dressing them up and taking them outside where the air is cooler, although there is not a lot of data to support those recommendations.
  • Signs of respiratory distress which indicate an emergent situation include very loud stridor, rapid breathing, and retractions mostly involving the neck muscles and nasal airways (flaring). Parents should call the pediatrician’s office for further instructions if they are unsure of the severity, call 911, or take their child to a nearby emergency department. (An urgicare center may not be appropriate for young children with acute respiratory emergencies.)
  • Some children can be treated at home with cool mist, ibuprofen (for throat pain and reduction of laryngeal inflammation and swelling), and plenty of fluids to drink (warm and cool beverages). Children with more severe respiratory symptoms are treated with steroids that are either injected into a muscle or given by mouth. A breathing treatment (of racemic epinephrine) can be given in the emergency department under careful monitoring of heart rate and breathing.
  • After the third night, symptoms begin to improve and usually resolve after 5-7 days. As the barking cough, stridor, and hoarseness improve, the infection may descend further down along the respiratory tract, causing tracheitis and bronchitis (inflammation of the trachea and upper bronchial tubes, respectively) and a looser, productive cough.
  • The initial laryngitis and subsequent tracheitis and bronchitis are viral infections — antibiotics will not be effective and will not be prescribed. Pneumonia is a rare complication of croup, and parainfluenza virus can also cause bronchiolitis and trigger wheezing in children with asthma.
  • Cough and cold medicines should not be used — they don’t work and can be dangerous for children to take. Honey should never be given to any infant under 12 months of age.
  • There is not a vaccine available to prevent parainfluenza virus and croup, which causes roughly 10% of pediatric hospitalizations due to respiratory infections.
  • As with all childhood infections, good and frequent handwashing can limit the spread of parainfluenza virus.


Older children, teenagers, and even adults can get croup, too. The symptoms of parainfluenza virus are usually milder than in infants and toddlers with less barking and little, if any stridor and respiratory distress. Occasionally, croup can make older folks pretty sick, as we’ll learn tomorrow on The PediaBlog.


(Google Images)