The Nexplanon implant is a long-acting reversible contraceptive method, consisting of a small, flexible rod placed just under the skin of the upper arm. This method offers highly effective, continuous pregnancy prevention for up to three years. Understanding when the implant becomes effective and how to manage the insertion site is important for safely resuming sexual activity after the procedure. The timing for when the implant provides protection depends entirely on when in the menstrual cycle it is inserted.
Determining When Protection Begins
The onset of contraceptive effectiveness is directly linked to the timing of the implant placement relative to the start of the menstrual cycle. If Nexplanon is inserted during the first five days of a menstrual period (Day one is the first day of bleeding), protection against pregnancy begins immediately. If the procedure occurs within this five-day window, no secondary birth control method is necessary. This immediate protection is possible because the body is not yet near ovulation, and the hormone level rises quickly.
If the implant is inserted at any other time during the cycle, a seven-day waiting period is mandatory to ensure full contraceptive coverage. During this week, an alternative barrier method, such as a condom, must be used to prevent pregnancy. This seven-day period allows the concentration of the hormone to build up sufficiently in the bloodstream to effectively block the reproductive process. Following the completion of this seven-day interval, the implant is considered fully effective for preventing pregnancy.
The timing rules also apply when transitioning from other hormonal methods to Nexplanon. For instance, if switching from a combination birth control pill, the implant is ideally placed the day after the last active pill was taken. If the insertion deviates from these recommended guidelines, the user must rely on a backup barrier method for the first seven days. Users should confirm the required waiting period with a healthcare provider and maintain alternative contraception until that timeline is complete.
The Mechanism of Hormone Delivery
The contraceptive effect of Nexplanon is achieved by the continuous release of a single synthetic hormone, etonogestrel. Etonogestrel is a type of progestin that works primarily by preventing the release of an egg from the ovary. By halting ovulation, the implant removes the possibility of sperm fertilizing an egg. Serum etonogestrel levels reach a therapeutic concentration within hours of insertion, which is why immediate protection is possible under the right circumstances.
The hormone also employs a secondary mechanism of action to reinforce its effectiveness. Etonogestrel alters the composition of cervical mucus, causing it to become thicker and stickier. This change creates a physical barrier that makes it difficult for sperm to travel through the cervix. A third contributing factor is the thinning of the uterine lining, making it less receptive to a fertilized egg.
The implant itself is a flexible rod, approximately four centimeters in length, containing 68 milligrams of etonogestrel. This hormone is gradually released into the body over the three-year lifespan of the device. This steady, low-dose delivery system ensures consistent hormone levels, which eliminates the possibility of user error associated with daily pills.
Immediate Care for the Insertion Site
While the question of when protection begins addresses safety from pregnancy, the physical recovery of the insertion site must also be considered for resuming normal activity. Immediately following the procedure, a local anesthetic is used, and the insertion site is covered with two types of dressings. The first is a pressure bandage or gauze wrap, which helps to minimize bruising and must remain in place for the initial 24 hours.
After 24 hours, the pressure wrap can be removed, and the area can be gently washed, but the smaller adhesive strips underneath must remain. These small strips, often called Steri-Strips, help the tiny incision heal and should be kept clean and dry for three to five days. It is common to experience mild soreness, tenderness, and some degree of bruising or discoloration at the site for up to two weeks. Over-the-counter pain relievers can be used to manage any discomfort during this healing phase.
To promote proper healing and prevent the implant from being dislodged, vigorous physical activity involving the insertion arm should be avoided for at least 48 hours. This includes heavy lifting, repetitive arm movements, or activities that could cause the arm to be bumped. Medical attention is necessary if signs of infection develop, such as fever, severe pain that worsens, spreading redness, or pus drainage from the site.