If an ADHD medication “zombifies” an individual, it’s too high a dose or not the right medication. The standard of care for ADHD medication is to start at the lowest dose and increase as and if needed. It can take several dose and/or medication changes to find the right one for each individual.
There are two types of stimulants: amphetamine (Adderall, Vyvanse, Evekeo…) and methylphenidate (Ritalin, Concerta, Quillivant…). Almost everyone does well on one type or the other, but not both. She may need to try the other type to know which is right for her.
Talk to her doctor about your concerns, including the rebound.
ADDitude Community Moderator, Author & Trainer on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism