A subdermal contraceptive implant is a highly effective, long-acting reversible contraceptive (LARC) method. This small, flexible rod, often known as Nexplanon, is inserted just beneath the skin of the upper arm. The implant continuously releases a low dose of the synthetic progestin hormone etonogestrel into the bloodstream. This steady delivery makes the method reliable over an extended period. The hormone primarily works by inhibiting ovulation and thickening cervical mucus, creating a physical barrier that blocks sperm. Understanding the implant’s duration and influencing factors is necessary for continued protection.
Standard Approved Duration of Contraceptive Implants
The duration for which a contraceptive implant is officially approved is determined by rigorous clinical trials that track its effectiveness over time. For the current etonogestrel implant, the manufacturer-approved and U.S. Food and Drug Administration (FDA) licensed duration is three years of continuous use. This three-year timeline is based on comprehensive data demonstrating that the implant maintains a consistently high level of efficacy throughout this entire period.
The contraceptive implant is recognized as one of the most effective methods of birth control, with an efficacy rate exceeding 99% during the three-year approved window. This reliability is largely due to the steady release of etonogestrel, which ensures the hormone concentration in the body remains above the threshold required to consistently suppress ovulation.
While the current recommendation is strictly three years, some clinical research has suggested the implant may retain its effectiveness for an extended period, potentially up to five years. However, regulatory bodies have not yet universally updated the official labeling for all users based on this data. Healthcare providers stress that the implant must be removed or replaced by the end of the 36th month to guarantee uninterrupted pregnancy prevention. Waiting beyond the approved duration risks a drop in hormone levels below the therapeutic threshold needed to reliably block ovulation.
Factors That Can Affect Reliability Over Time
While the three-year duration applies to the majority of users, specific biological and external factors can influence the implant’s reliability as it nears its expiration date. The effectiveness of the implant relies on maintaining a circulating concentration of etonogestrel above a minimum level necessary to prevent an egg from being released.
Higher body mass index (BMI) is one factor that has been studied for its potential impact on the implant’s effectiveness. Although the implant is considered highly effective across all weight categories, individuals with a significantly higher body weight may metabolize hormones differently or have a larger volume of distribution for the drug. Older prescribing information noted that the clinical experience in heavier women was limited, leading to a caution that the contraceptive effect might be lower toward the end of the three-year period.
Some clinicians may therefore discuss the possibility of earlier removal, perhaps slightly before the 36-month mark, for patients with obesity to ensure hormone levels do not prematurely dip below the protective threshold. Many medical bodies still consider the implant reliable for the full three years regardless of weight.
The impact of certain medications is another significant consideration that can reduce the implant’s lifespan. Medications that act as hepatic enzyme inducers can accelerate the metabolism of the etonogestrel hormone in the liver, causing it to be broken down faster than normal. Specific examples include the antibiotic rifampin, some anti-seizure drugs (anticonvulsants), and certain HIV medications. The herbal supplement St. John’s Wort also falls into this category of enzyme inducers. For people taking these substances, the implant’s effectiveness may be compromised sooner than three years, necessitating the use of a backup contraceptive method or an earlier replacement.
Expiration, Removal, and Replacement
When the contraceptive implant reaches the end of its approved duration, its effectiveness is no longer guaranteed, making timely removal necessary to avoid unintended pregnancy. The implant does not suddenly stop working, but the diminishing release of etonogestrel means the suppression of ovulation becomes unreliable. Once the hormone level drops too low, the body’s natural reproductive cycle can resume.
The removal procedure is a minor, in-office surgical procedure performed by a trained healthcare professional. It typically involves injecting a local anesthetic to numb the insertion site, making a small incision near the end of the rod, and gently extracting the implant. The procedure is generally quick, often taking only a few minutes, although it can be slightly more involved than the initial insertion.
Following the removal of the implant, fertility returns rapidly, often within the first month. Because the hormone is no longer being released, the body quickly clears the remaining etonogestrel from the system, allowing ovulation to resume almost immediately. This rapid return to pre-treatment fertility is one of the key benefits of this LARC method.
If the user wishes to continue with the implant, a new device can be inserted immediately following the removal of the old one, often through the same incision site. This simultaneous exchange ensures continuous contraceptive protection without any gap. Alternatively, removal is a natural transition point for a person to select a different form of birth control or stop contraception entirely if they are planning to become pregnant.