To my faithful student, Twilight Sparkle,
Certain mind-altering plants, spells, compounds, or phenomenon are indeed bad for the underlying health concerns, or for the possible repercussion of acting day to day with your mind inebriated. Used in moderation and responsibly there are a great many helpful or benign uses for nearly anything of the sort. Giggle grass, for example, is sometimes used as an alternative to anesthesia for stressful visits, such as to a dentist.
That said, these should be used in moderation, and only under supervision.
Further, I impress upon you that aforementioned mind-altering things prescribed by a licensed medical doctor (familiar with pony biology) are generally exempt from 'only under supervision' but you should follow the instructions. If you dislike how they make you feel or act, discuss them with the doctor for other options.
Your loving mentor,
Princess CelestiaPS. This reminds me Twilight, have you been taking your prescription regularly?