At first a child may have an upper respiratory infection for several days before the onset of cough. If the upper airway becomes more obstructed, the labor of breathing becomes intense. Children with viral croup may have a fever. Symptoms often worsen at night and with crying. Possible airway obstruction is a major concern.
Most croup is caused by viruses and occasionally by bacteria.
Most children with viral croup are between the ages of three months and five years. Symptoms are most severe in children under three years of age. The incidence of croup is more common among males and during the cold season of the year. This frequently begins at night with a sudden onset. The child usually has no fever with spasmodic croup.