My son started on methylphenidate at just under 5. He takes a liquid, and we’ve moved the dose up a few times. At 4 he was on 3.75 mL once a day, at 6.5 he has 5mL twice a day.
We monitor growth closely, and loss of appetite has been the main side effect, so he eats like a mad man from 4-8:30 every night once the drug wears off. We added in a fortified chocolate protein drink for school lunches this year to make sure he has something before the school nurse gives the mid day dose.
We give at least one dose every day even on weekends because I also was recently diagnosed and discovered I do so much better with emotional regulation if I take my medicine every day. It turns out the weekend breaks we were giving weren’t helping, and we can address the calorie intake differently. For both my son, as we were learning about his best match dosage, and for myself, the other side effect we experience is headaches and we need to drink a lot of water to prevent that. At one point I thought he was having jaw pain, which can be a side effect, but we learned he was cutting molars!
(Sadly, I do not have the loss of appetite because I’d love to lose some weight!)