This is a multi-center, open-labelled study to confirm the safety as main objective, and consisting of minimum 1-week screening period and 2-week treatment period. The subjects who meet the inclusion criteria are to be placed on one of the following two regimens according to their ages at the start of treatment period: once daily administration of levocetirizine at a dose of 1.25 mg (in the morning) to infants aged between 6 months and 1 year old (younger age group), and twice daily administration of levocetirizine at a dose of 1.25 mg (in the morning, in the evening before sleep) to infants aged between 1 year and 2 years old (older age group).