my son was on ritalin for about 6 months but he lost too much weight. This was back about 8 years ago. They tried many different meds before settling in on a combo of adderall and clonidine for him. He has been on this ever since and has only had to have one increase since he started. He is now 12 1/2 years old and is right on for height and weight (actually he is one of the taller boys in the class). We have been very happy with adderall.
Good luck with whatever you choose. I know from my own experience with meds, one medicine isn't for everyone.
Kathy