People have been on meds for over 20 years (see study by Weiss and Hechtman) the longest cohort study around. Add in the fact that the meds have been around for over 50 years, you know that they are generally safe.
But…..ADHD management is about lifestyle change. As Indigenuity and ADDled suggest, it is about finding lifestyle choices that matter. The most important factor is that you have control over the duration and timing of the medications.