In the United States, approximately 3% of children are affected by croup each year. It is most common in children between the ages of six months and three years. One of several viruses usually causes it, but 75% of all cases are caused by parainfluenza virus. However, not all kids who catch these viruses will get croup; some will simply have cold symptoms.
Additionally, bacteria can cause croup, but it’s much less common. And since croup is most likely caused by a virus, antibiotics won’t help. It will just need to run its course.