"i have had implanon in for two years. it has been an amazing &quot;birth control&quot;. i do not take very many precautions and i have never had a pregnancy scare. i did not gain weight while being on this, i actually lost weight. the only negative effect this has had on me is my menstrual cycle. i am constantly on my period (spotting). i go several months spotting with an occasional couple days off. i absolutely hate this effect the implanon has on me, but it may work out better for others. most definitely most effective as far as birth control."