"i&#039;m a 46 y.o. female and have been taking vyvanse for approximately 3 months. i started out on 50mg in the morning and it worked great by giving me energy and completing projects. however, i would get tired after 8 hours. after 1 month of taking 50mg x1 a day my doctor switched me to 30mg twice daily to prevent that tired feeling after 8 hours. after 2 months of taking 30mg x2 a day i&#039;m tired a lot and seemed to have already built up a resistance to it. maybe i just need to increase the dose, not sure. this medicine worked great at first for adhd and i&#039;m hoping i can increase the dose and feel energetic and focused again. the side effects i have experienced are, weight loss (13lbs) the first month but gained 8 lbs back, and have bad breath."