http://www.medications.com/effect/view/29341 Sorry guys. The post below is mine and I left out a critical part of the entry. My three year old daughter was put on Allegra (along with the Singulair and Nasonex) in mid-March which is when her sleeping patterns changed. I've researched the side-effect Tue, 08 Apr 2008 21:58:58 -0400 http://www.medications.com/effect/view/29341?item=6872 My daughter is 10 and was put on Singulair (5 mg 1x a day) and Allegra (2x a day) 3 years ago. This combination was wonderful! No more seasonal allergies at all. About a year or so we started seeing mood swings. In January, the stomach aches started daily. http://www.medications.com/effect/view/29341?item=6872 Wed, 09 Apr 2008 15:54:56 -0400 http://www.medications.com/effect/view/29341?item=6917 i only know about singulair and i do know that it causes sleeplessness in some children. just read through the posts from the last month or so, you'll see a very distinctive pattern. http://www.medications.com/effect/view/29341?item=6917