The birth control implant (Nexplanon) works immediately if it’s inserted during the first five days of your period. If it’s placed at any other time in your cycle, you need to use a backup method like condoms for seven days before it’s fully effective.
That’s the short answer. But timing depends on your specific situation, including whether you’re switching from another method, and there are a few practical things worth knowing about what to expect in those first days and weeks.
The 7-Day Rule
The implant is a small, flexible rod placed under the skin of your upper arm. It steadily releases a hormone that prevents pregnancy in three ways: it stops your ovaries from releasing eggs, thickens the mucus in your cervix so sperm can’t get through, and changes the lining of your uterus.
When the implant goes in during days 1 through 5 of your menstrual cycle (day 1 being the first day of bleeding), those hormonal effects kick in fast enough that no backup contraception is needed. Your body is already at a point in the cycle where the implant can take over right away.
If it’s placed on day 6 or later, those changes need time to build up. The standard guidance from the CDC is to use condoms or abstain from sex for seven days after insertion. After that week, you’re fully protected.
Switching From Another Method
You don’t need to wait for your next period to get the implant placed, even if you’re switching from pills, a patch, a ring, or an IUD. Your provider can place it at any appointment as long as there’s reasonable certainty you’re not pregnant.
The same 7-day backup rule applies if it’s been more than five days since your last period started. If you’re currently on another hormonal method, one practical option is to keep using that method for the first seven days after the implant goes in, then stop.
Switching from an IUD has an extra consideration. If you’ve had sex during your current cycle and it’s been more than five days since your period, your provider may recommend keeping the IUD in place for seven days after implant insertion before removing it. This avoids a gap in protection where residual sperm could cause a problem.
How Effective It Is
Once the implant is working, it’s one of the most effective contraceptives available. A large real-world study tracking over 7,300 Nexplanon users found a Pearl Index of 0.02, meaning roughly 2 pregnancies per 10,000 women per year of use. Only 3 pregnancies occurred during active use across the entire study. That puts the implant in the same effectiveness tier as sterilization, but it’s fully reversible.
The implant is FDA-approved for three years, but research suggests it remains highly effective beyond that window. A study published in Human Reproduction followed over 200 women who kept their implant in for five years and found zero pregnancies during years four and five. A separate U.S.-based study tracked 123 women through four years of use and 34 through five years, also with no pregnancies. While three years remains the official recommendation, this data is reassuring if your replacement appointment gets delayed by a few months.
What the First Few Months Feel Like
Right after insertion, your arm will be wrapped in two bandages. The outer pressure bandage should stay on for 24 hours to minimize bruising. Underneath that is an adhesive bandage that you’ll want to keep clean, dry, and in place for 3 to 5 days while the small insertion site heals. Some bruising and tenderness around the site is normal.
The bigger adjustment is your bleeding pattern. In the first three months, about one-third of implant users have a favorable pattern of lighter or less frequent bleeding. But prolonged episodes lasting more than 14 days, or more frequent spotting than usual, are more common in the early months. This is related to the higher hormone levels the implant releases when it’s new. The spotting and bleeding days often add up to fewer total days than a normal period, but they show up at unpredictable times, which can be frustrating. For most people, bleeding patterns settle into something more predictable after the first few months.
Fertility After Removal
The implant’s effects wear off quickly once it’s taken out. Ovulation can return in as little as 7 to 14 days after removal, regardless of how long the implant was in place. Most people see their natural cycle return within one to two months. Unlike some other long-acting methods, there’s no extended delay in fertility, so if you’re having the implant removed and don’t want to get pregnant, you’ll need another method right away.