I have two comments to make: 1. When I took the DEX treatment with my second pregnancy I had 3 angry outbursts. I have never been out of control before or since. I felt very unsettled on the DEX. I know our kids are on a replacement dose but if kids are getting to much cortisone I am sure it could make them more fragile in the emotion department. 2. My kids do not have many outbursts or temper problems, but my best friends 5 year old sure does. I guess what I am saying if your child is over or maybe even under medicated I do believe it can cause behavior issues, but I also think 4-5 year olds can really act out and it could just be a "phase". Good Luck.