"i am a 15 year old female. i started taking vyvanse around 5 months ago. when i first started taking it i saw a difference immediately. i was always on 50mg. it made me very irritable and emotional the first times i took it. currently, i&#039;ve been taking this for a few months and it is starting to become less effective on me. i am now starting to double up my doses taking 50mg to 100mg a day. it gets me through the day and keeps me awake. not to mention excellent grades in school."