It depends on the individual’s metabolism, genes, and neurotransmitter functioning. Often, physicians increase the dose when it wears off quicker than it’s supposed to. Sometimes that helps, sometimes it becomes too strong of a dose. There are many different ADHD stimulants in two types: amphetamine (Vyvanse, Adderall…) and methylphenidate (Ritalin, Concerta). People do well on one type or the other, but not both.
ADDitude Community Moderator, Author & Mentor on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism