I wouldn’t be surprised — if you are young and otherwise healthy, how often do you check your blood pressure or see your primary care doctor? Knowing high BP and heart problems are a potential side effect, how often does the Psychiatrist prescribing these things check at a follow-up?
Briefly tried to take a medication also used for ADHD that wasn’t adderall, ended up in the ER as I check my BP regularly. Some younger kids might not equate a side effect of a bad headache with anything more serious..