My nephew started vyvanse (lisdexamfetamine) 30mg. he is having anxiety. he was giving atarax 25 mg for it. can he take both together. he is 10 yr old. 128lbs. 4'11 tall?

Side effects: Anxiety is a common side effect of all of the stimulant class for ADHD. There are several alternatives. Is the atarax (hydroxyzine) to induce "sleepiness" in hopes of reducing anxiety? Trying a different stimulant is an option. Non stimulant drugs are another option. Yes, the two drugs you mention may be taken together. Don't forget to maximize behavior modification strategies also!