birth control
"I've had two implanon's in four years. with the first one I gained around 20kgs, obviously not from the implanon itself but more likely as a result of a massive hormone change. I had the first one for almost three years before I decided to have it removed as it caused such a profound hormone imbalance I ended up with a harmless but embarrassing discharge for the last nine months. 
The second implanon I had implanted in early 2015, it started off fine- one menstrual cycle every 2-3 months, but now I am lightly bleeding for two weeks of every month with terrible hormonal acne and cramps. 
This device has been a wonderful thing for me most of the time so I allow it a bit of leeway in terms of unwanted effects."