"i got nexplanon in november 2012, i didn&#039;t know when it started working because i was in bootcamp but i don&#039;t think i got my period for 3-4 months. when i do get my period, i don&#039;t know how long it will last because the 1st one i got was 4 days, and the one after was 2 weeks. the only really bad thing i&#039;ve found is weight gain. i&#039;ve been able to get rid of some of the weight, but not enough to where i feel comfortable with myself again. i think i gained 22lbs i went from 116lbs to 138lbs. aside from that, it works great."