Oh, I forgot to add that my son has started to lose weight, which...

I can't believe I stumbled upon this website. Our 3 year old son has been on singulair for over one year. During this time, he has had wild mood swings, crys at the drop of a hat, has regular red hives all over his skin, and has at times seemed very depressed and angry. We thought there was something wrong with him mentally, and did not know where to turn. Once we stopped his singulair doses, all the symptoms went away, and he is a happy and healthy 3 year old, but is behind on his speech, potty training, and general learning skills. Merck needs to be sued by all of us parents. They are responsible for the destruction or interruption of many little lives due to singulair.