How long will Vyvanse's effect last? Depends how much you took, if you took 70mg probably 12 hours or so but if you took a real high dose like 140mg probably 18 hours maybe a little more. A little more kick to it than 5 hour energy.Lisdexamfetamine is a prodrug of dextroamphetamine.Amphetamine is a scheduled drug and if you do not have a prescription it is against the law to obtain or use. Rarely, amphetamine can cause heart failure and psychosis.isdexamfetamine is a prodrug of dextroamphetamine. Amphetamine is a scheduled drug and if you do not have a prescription it is against the law to obtain or use. Rarely, amphetamine can cause heart failure and psychosis.