Suggest Treatment For Difficulty In Gaining Weight

Hi, I am a 20 almost 21 year old female about 96 lbs and 5 6 . I have been thin all my life and i have some problems gaining weight most likely because I can t seem to get enough calories. I heard about something called apetamin. I would like to try it because I ve heard a lot of success from it but is it safe? What exactly is it?