Etonogestrel
"I had the implant put in about four months ago.  While it's been nice not having a period and not having to take a pill every day,  I wouldn't recommend it. My arm never stops itching, which is incredibly annoying after the first few days. I have gained about thirty pounds and a bunch of stretch marks. ... and I developed severe acne- I've never had acne before the implant.  The worst side effect is the random pain at the insertion site and the random bruising. While I haven't gotten pregnant, the side effects suck!"