My son has used Concerta for a little over a month and it has been a great experience. He is so happy being on it. I know it is normal to have some side effects for the first few days, ie stomach and head aches, and some insomnia, and all that went away by the fourth day. My question is about drug holidays. I am hesitant to keep him off on weekends and holidays because I don't want him to have to go through the side effects again. Does this make sense, and once a person has been on it awhile, do they not experience the same effects when starting again after a few days or weeks? Thanks in advance for your great advice.