Nexplanon Does NOT Completely Stop Working One Month After Expiration
Nexplanon does not abruptly lose all contraceptive effectiveness at exactly 3 years, and evidence suggests it likely retains significant protection one month beyond the approved duration, though replacement at 3 years remains the FDA-approved recommendation. 1, 2
Understanding Nexplanon's Mechanism and Duration
The etonogestrel implant works primarily by suppressing ovulation, maintaining serum etonogestrel levels above 200 pg/ml throughout the approved 3-year period. 3 The contraceptive effect is not an "on-off switch" but rather depends on maintaining hormone levels sufficient to prevent ovulation.
Evidence for Extended Effectiveness
- Research demonstrates that ovulation suppression continues well into the third year, with ovulation occurring in less than 5% of users even after 30 months of use. 4
- Recent real-world data shows no documented pregnancies during a fourth year of use in observational studies, though this extended duration is not FDA-approved for routine practice. 1
- The pharmacokinetic profile shows that etonogestrel levels decline gradually over time but remain in the contraceptive range throughout the approved duration, suggesting a buffer period exists beyond 3 years. 3
The 3-Year Replacement Recommendation
The FDA-approved duration is 3 years, and the implant should be replaced by the end of the third year. 2, 5 This recommendation provides a safety margin to ensure contraceptive efficacy before hormone levels potentially decline below the threshold needed to prevent ovulation.
Clinical Guidance for Your Situation
If your Nexplanon is one month past the 3-year mark:
- You likely still have contraceptive protection, but this is beyond the approved duration and carries increasing theoretical risk. 1
- Schedule immediate replacement rather than relying on extended use, as the FDA approval and all major guidelines recommend removal/replacement at 3 years. 6, 2
- Use backup contraception (condoms) until a new implant is inserted to eliminate any pregnancy risk during this uncertain period. 6
- After new implant insertion, continue backup contraception for 7 days to ensure full contraceptive coverage. 6
Important Caveats
- Women taking hepatic enzyme-inducing medications (efavirenz, nevirapine, most protease inhibitors) may have reduced efficacy even during the approved 3-year period and should use additional contraceptive methods. 1
- Body weight does not affect the approved duration—obese women can use implants with the same 3-year timeframe. 6
- Fertility returns rapidly (within 1 week of removal), so any delay in replacement creates pregnancy risk if no backup method is used. 5, 3
The exceptional effectiveness of Nexplanon (failure rate <0.05% during approved use) makes it one of the most reliable contraceptive methods available, but this reliability depends on adherence to the 3-year replacement schedule. 6, 7