Does the granule form have as many side effects as the pills?

My son, just now turned seven has been on Singulair since last October 08. I did not see a big improvement in the allergic rhinitis, though coughing with laughing was somewhat improved. I stopped it over the summer, and restarted it in Sept on the recommendation of the allergist when my son had his first ever real asthma attack after a big fire in our area. I feel he has become very aggressive and angry since school started, but I can't tell if it's school or Singulair. I have been giving him the granules since he is allergic to many things and sensitive to food dyes, so my question, when aggression is noted in kids, has the form of Singulair been taken into account?