Recurrent episodes during the night for several days is the general rule, but some nights may be skipped between attacks. Treatment at home by exposure to steam in the bathroom or to the cool night air is sufficient to break the attack. The child often arrives in the emergency room with surprised parents because the attack has been broken during the ride by the night air. Racemic epinephrine will break the attack if needed. The major differential diagnosis is between spasmotic croup and viral croup.
Complications are exceedingly rare.
Diphtheria is a rare cause. The illness is generally quite mild with sore throat, hoarseness, cough, and possibly mild inspiratory stridor. Respiratory distress is rare with the exception of young infants. If diphtheria is the cause, respiratory distress with airway compromise is quite marked secondary to the pseudomembrane blocking the laryngeal inlet . Complete obstruction and respiratory arrest may occur.