I take 60mg and it last 6-7 hours if I am lucky, despite the company's claim that it lasts 12. The study that stated 12 hours was conducted on children, not adults.
How Long Does A Vyvanse 50 Mg Pill Last?
Well ive been awake for 2 days straight on my 50 mg..guess is just depends on your body type because I'm tiny and hot so it lasts longer with me :)