I can relate to this. I have an 18 year old who has never found that medication actually helped her. Some did contribute to increased anxiety and others she said "made her sick" among other complaints so she has never been consistent in taking it. Recently we noticed that a bottle of Concerta that had been only touched sporadically in the last several months went from having about 27 pills down to four in a matter of about two weeks. Interestingly just prior to that, we had yet another of our "discussions" about giving the meds a try on a consistent basis rather than one here and there which she argued about and refused. She turned the tables on us saying "we should be glad she has decided taking it,...etc etc.." but I expressed concern that there were too many gone for the time frame. SHe denied taking it unnecessarily or other misuse (Like sharing it with her friends), however, when she went to get a prescription refills some time later, between the time she got from the drug store to home, five pills were missing-stating she was going to take one but spilled a few and did not bother to pick them up. A friend of hers accompanied her at that time as well. It is hard to prove and she always has an answer when we question her (and her friend) but we have gone to "dispensing" it to her- one a day and now she has reverted to not taking it...I suspect abuse but because of her inability to find the right dose, it might not affect her a whole lot.

She has some other risky behaviors of late that add to this (like helping herself to alcohol even though she is not legal age and making no excuses for it except that she wanted it to "chill out".) School has not really improved either which is why I question whether it is her actually taking it or not and she never has any money it seems so I don't think she has caught on to selling it but perhaps is giving it away.