my 4 year old daugther was on zyrtec for almost a year,she has inlarged tonsils and allergic to dust,the whole time she was on it she snored so bad you could hear her in the other room,and had bouts where i believed she wasnt breathing, the doctors wanted to remove her tonsils.the whole time she was on it she still had runny nose and the docs told me to take her off zyrtec if i felt it wasnt helping,after i took her off it within a few days her snoring stopped,i totally believed she was allergic to the zyrtec and it bothers me no doctor figured this out and i hope this dosent cause her any long term problems,her tonsils havent been red anymore either.no more snoring and i have chosen to keep her tonsils..