It takes all hormonal forms of birth control 1 week to become effective. Once someone has been on the Nexplanon for at least 1 week, they are 99% protected from pregnancy for up to 3 years, even if ejaculation in the vagina occurs.
Since unprotected sex did occur before the 7 days, the Nexplanon was not reducing the risk of pregnancy. Emergency Contraception is an option, which can be taken up to 5 days, and works by delaying ovulation.
Remember, hormonal methods of birth control ( like the Nexplanon) do not protect against STIs. Only condoms and dental dams can protect against STIs. You can get condoms and dental dams for free at Teen Clinic!
If you have any more questions, or want to make an appointment at Teen Clinic, give us a call! 303-442-5160