My 7 year old son has ADHD and has been on Daytrana (10mg) for about six months. Until recently, it has worked wonderfully and his symptoms (lack of focus, difficulty following directions, hyperactivity) have greatly improved. About two weeks ago, rather abruptly, his symptoms have returned full force. It is if he has stopped taking his medication. I am wondering if he has built up a tolerance to the drug? I hate to think this, since he has only been on the drug for six months, but my husband and I can't think of any other explanation.