Small capsules containing a hormone (progestogen) are implanted just under the skin on the underside of a woman’s upper arm using a minor surgical procedure. 

The hormone is released in very small daily doses into the woman’s bloodstream, preventing pregnancy for three to seven years (depending on the kind of implant used). 

The implant is extremely effective against pregnancy (over 99%), but it does require a minor surgical procedure and is palpable and slightly visible under the skin. 

Once it is inserted, it requires no additional action by the user, offering continuous protection over a long period of time. 

Possible side effects and effects on pleasure are similar to oral contraceptives.  Although it can cause irregular menstrual bleeding, it does tend to reduce menstrual pain.