For harmful affects of it I'd say stop.. is she eating much? It will make you eat a lot less.. I'm surprised that she's calm, perhaps she is only calm physically?
I thought the point of it is to make them immune to the effects of ADHD since both release the same chemicals in the brain.. though I'd also be worried that this could cause damage similar to an overdose.
I'm no doctor though! I kind of wish I'd carried on taking it for the sake of curing my ADHD by adulthood, its still a major problem, makes everyone treat me like a kid.. well I do run around like one. My only solution is sitting deadly still and not interacting with people, though I have had some success with self hypnotism/meditation
also the hair thing sounds horrible.. I've never heard of anyone having that kind of a reaction to amphetamines, that would make me stop..