Hi Dr My Boy Is 2 Years 8 Month And

Hi Dr
My boy is 2 years 8 month and have a chronic problem with Allergies and sinus. they removed his tonsils in February and we thought the problems will go away. but still every season change or even if we go away for vacation we always return with a sick boy. runny nose, coughing ext. the only thing that seams to be working is Celestamine. is it bad for him. can I give it to him with every season change or even when his nose starts running?