http://www.medications.com/effect/view/28536 I have a 3 year old son that was diagnosed back in December with allergies and was prescribed Zyrtec and Singulair, after taking them for a while we noticed that he became very belligerent so we called the Allergist and they took him off the Singulair and p Sat, 29 Mar 2008 00:40:59 -0400 http://www.medications.com/effect/view/28536?item=6118 My 5 year old daughter had been taking Clarinex daily for about 2 years because of bad allergies. I had not noticed any change in her behavior or personality during that time frame. However, I did not like having to give her medicine every day so I began http://www.medications.com/effect/view/28536?item=6118 Tue, 22 Apr 2008 17:17:00 -0400 http://www.medications.com/effect/view/28536?item=7526 My son (now 4) was on Clarinex for about 36 hours when he was about 2 1/2 yrs old. Needless to say, after his horrid behavior, we took him off of it. He's been on Singulair for about a year now and is just fine. I only put him on it when his asthma symptom http://www.medications.com/effect/view/28536?item=7526