Implanon is one of the brand names for the etonogestrel contraceptive implant developed by Merck & Co. It is a type of long-acting, reversible contraception that's implanted under the skin of the upper arm by a medical professional. It contains etonogestrel; it is said to be the most effective form of women's birth control. It has a failure rate of only .05% and is more effective than tubal sterilization. Its use began in Indonesia in 1998. Its use in the United States began in 2006. There are now approximately 11 million women who use Implanon and the implant's other brands.