What Happens If You Keep Nexplanon in Too Long?

Keeping Nexplanon in your arm beyond its three-year FDA-approved window does not trigger an immediate health emergency, but it does raise questions about whether the implant still prevents pregnancy and whether leaving it in place makes eventual removal harder. The short answer on contraception is surprisingly reassuring: clinical studies have tracked women using the implant for up to five years and found zero pregnancies during the extra time. But the picture gets more complicated when you factor in physical changes in the tissue around the implant, edge cases involving body weight, and the practical reality that many clinics are not yet set up to counsel patients on extended use.

The Implant Still Prevents Pregnancy Past Three Years

Nexplanon releases etonogestrel, a synthetic progestin, into the bloodstream. The three-year label reflects the timeframe for which the manufacturer submitted regulatory data, not necessarily the moment the hormone runs out. Researchers have studied what happens when women simply leave their implants in place, and the results are strikingly consistent: no pregnancies show up in years four and five.

One of the key studies followed over 200 women who used the etonogestrel implant for at least five years. During the extra two years of follow-up beyond the label, not a single pregnancy occurred. The overall five-year pregnancy rate was 0.6 per 100 woman-years, which is extremely low and comparable to the rate seen during the approved period.¹ A separate U.S.-based study tracked 237 implant users through years four and five and likewise documented zero pregnancies, calculating a failure rate of 0 per 100 woman-years.²

A later analysis of those same study participants, after they had contributed even more follow-up time, continued to show no documented pregnancies among implant users during two years of post-expiration use. The calculated failure rates at both four and five years remained at zero.³ These are not small, sloppy studies. Combined, the follow-up data represents hundreds of women and hundreds of woman-years of observation. The evidence strongly suggests the implant continues working well through year five.

Why the Label Says Three Years If It Works Longer

The gap between what the FDA label says and what the clinical evidence supports is a source of real confusion for patients and, frankly, for many clinicians too. The three-year duration on the label reflects the data the manufacturer originally submitted to get approval. Extending the label would require additional regulatory steps, and researchers have noted that the logical path forward would be for organizations like the World Health Organization to evaluate the extended-use evidence and issue their own recommendations, much as they have for other long-acting contraceptives.¹

The Society of Family Planning has already taken a step in this direction, issuing a clinical recommendation that reviews the evidence supporting extended use of several long-acting reversible contraceptives, including the etonogestrel implant, beyond their FDA-approved durations.⁴ But professional guidance from specialty societies does not carry the same weight as an FDA label change, and many primary care offices and family planning clinics still default to the three-year replacement timeline.

A mystery-shopper study that called 59 U.S. clinics found that roughly two-thirds either recommended replacing the implant at three years or could not provide any information about extended use over the phone. Only about a third of clinics offered extended use as an option.⁵ If you call your provider and they insist it must come out at three years, that is the standard they were trained on. It does not mean the implant is dangerous at three years and one day, but it does mean you may need to advocate for yourself with evidence in hand if you want to discuss keeping it longer.

Does Body Weight Change the Math?

This is one of the questions people worry about most, and the news is generally good. Higher body weight has been theorized to dilute hormone concentrations and potentially reduce efficacy, but the data does not bear this out for the implant during its approved use. A large study found that the three-year failure rate for implant users was less than 1 per 100 woman-years and did not vary by body mass index.⁶

A systematic review looking specifically at implant effectiveness in users with overweight and obesity found a similar pattern. Among women with a BMI of 25 or above, none of the reviewed publications reported pregnancies among those with overweight. Two publications reported one pregnancy each among users with obesity, but the resulting pregnancy rates were vanishingly small. Interestingly, the three pregnancies that did occur across the reviewed studies all happened in users with a BMI under 25.⁷

What remains less clear is whether body weight affects efficacy specifically during extended use in years four and five. The extended-use studies did not break down results by BMI in the same detailed way. Given that etonogestrel levels do decline gradually over time, it is at least plausible that higher body weight could become more relevant as the hormone reservoir shrinks in later years. If you have a higher BMI and are considering keeping the implant past three years, this is worth discussing with a provider who is familiar with the extended-use literature.

Rare Pregnancies During Extended Use

The large studies described above found no pregnancies in years four and five, but that does not mean the risk is literally zero forever. A case report documented two pregnancies in women during the fourth year of implant use. One of these was a tubal ectopic pregnancy in a patient whose implant had been placed three years and five months before she presented.⁸

Ectopic pregnancies are already a known risk with progestin-only contraceptives in general: the hormone thickens cervical mucus and suppresses ovulation, but if an egg does get released and fertilized, the altered tubal environment can sometimes trap it outside the uterus. This is rare under any circumstances, and the implant overall reduces the absolute risk of both normal and ectopic pregnancy compared to using no contraception at all. Still, these case reports matter because they suggest that the protection in year four, while very high, is not as ironclad as the large trials initially implied. If you experience abdominal pain or unusual bleeding with an overdue implant, pregnancy including ectopic pregnancy should be on the list of things to rule out.

What Happens to the Implant Physically

The implant is a flexible plastic rod about the size of a matchstick, and it sits just under the skin of the upper arm. Over time, tissue can form around it. For most people, the implant stays where it was placed and remains easy to feel through the skin. But in some cases, particularly when the implant has been in for many years or was placed deeper than intended, the rod can become embedded in tissue or, in rare instances, migrate from its original location.

When an implant is non-palpable, meaning you cannot feel it under the skin, imaging is needed to find it. Ultrasound is the usual first step. If that does not locate the rod, MRI can detect implants that are deep or have migrated into muscle tissue. In extremely rare cases where the implant has migrated into the chest, a CT scan may be needed.⁹ Migration to the lungs is exceedingly uncommon and is associated with implants that entered a blood vessel at placement, not with simply leaving an implant in too long. But the longer the device stays in place, the more time tissue has to encapsulate or anchor around it, and that can make removal more complicated even if the implant has not actually moved.

Why Removal Can Get Harder Over Time

A standard Nexplanon removal takes a few minutes in a clinic: a small incision, some gentle traction, and the rod slides out. When the implant has been in place for many years, the surrounding tissue may have formed a fibrous capsule that grips the rod more tightly. Deep placement or weight gain since insertion can push the device further from the skin surface. None of this is life-threatening, but it can turn a routine office procedure into something more involved.

In one reported case, a 21-year-old woman suffered an ulnar nerve injury during an in-office attempt to remove a deeply implanted Nexplanon. The damage resulted in nerve palsy that required surgical exploration, excision of a neuroma, and a nerve graft to repair.¹⁰ This is an extreme outcome and reflects a deeply placed implant rather than simply an overdue one, but it illustrates why providers become cautious when an implant cannot be easily felt.

A case series of difficult removals found that some implants had become adherent to sensory nerves, and another was located within the biceps muscle. In those cases, ultrasound-guided localization, general anesthesia, and wider surgical exposure were needed to get the implant out safely.¹¹ The takeaway is not that leaving the implant in for an extra year will cause nerve damage, but that the longer you wait, the more important it becomes to confirm you can still feel the rod under your skin. If you cannot, get imaging done before anyone tries to pull it out.

Fertility After a Late Removal

One common worry is that leaving the implant in longer than intended could somehow damage fertility. The evidence does not support that concern. Fertility returns quickly after implant removal regardless of how long the device was in place. A review of implantable contraceptives found that pregnancy rates after removal ranged from 76 to 100 percent within one year, which is no different from rates seen after stopping any other contraceptive method.¹²

The mechanism here is straightforward. The implant works by releasing a hormone that suppresses ovulation and thickens cervical mucus. Once the rod is out, those effects wear off rapidly, usually within days. There is no accumulation of the drug in body tissues that lingers for months afterward. If you had the implant in for four or five years and then have it removed, your timeline to potential pregnancy should look the same as someone who had it removed right at three years.

Barriers That Keep Implants in Too Long

In an ideal world, everyone would have easy access to a provider who can remove or replace the implant on schedule. In reality, many people end up with an overdue implant not by choice but because of logistical obstacles. A study of postpartum women with long-acting contraceptives found that cost, lack of insurance, and difficulty getting an appointment were common barriers to removal.¹³

This is worth acknowledging because the extended-use data exists partly to reassure people in exactly that situation. If your implant expired a few months ago and you have not been able to get in for a replacement, you are very likely still protected against pregnancy. The evidence through five years is strong. That said, the data thins out past year five, and no major study has tracked efficacy past that point. If you are several years past the label date, the urgency of getting the implant dealt with increases, both for contraceptive reliability and to avoid making removal more complicated than it needs to be.

Bleeding Pattern Changes With an Aging Implant

Nexplanon is notorious for causing unpredictable bleeding, and this is one of the top reasons people want it removed. As etonogestrel levels slowly decline over the years, your bleeding pattern can shift. Many users find that they have very light or absent periods during the first couple of years, then start experiencing more frequent or irregular spotting as hormone levels taper. By year four or five, some women report a return of regular-seeming cycles, which actually reflects the hormone dropping low enough for the ovaries to partially “wake up.”

A return of regular bleeding does not necessarily mean the implant has stopped working. Ovulation suppression can persist even at lower hormone levels. But a clear shift toward regular monthly bleeding in a long-overdue implant is a sign that the contraceptive margin is narrowing, and if preventing pregnancy is important to you, it warrants a conversation with a provider sooner rather than later.

When an Implant Has Been in for Many Years

Some people discover they have had their implant in for seven, eight, or even ten years, often because they forgot about it or could not access care. At that point, there is essentially no clinical trial data on efficacy. The hormone is likely still releasing at some minimal level, but whether it is enough to reliably prevent pregnancy is unknown. The physical concern at that stage shifts more toward removability. An implant in place for a decade may be more encapsulated, and if it has become non-palpable, the removal process could require imaging and potentially referral to a specialist.

If you are in this situation, the implant is not dangerous to leave in from a toxicity standpoint. The etonogestrel rod is biologically inert as a physical object, and the hormone itself does not build up to harmful levels over time. But relying on it for contraception past year five is a gamble that no study has quantified. And from a practical standpoint, the sooner you address an extremely overdue implant, the simpler the removal is likely to be. A provider who can feel the rod easily will have a much easier time getting it out than one who needs to hunt for it with ultrasound.

What to Do If Your Implant Is Overdue

If your three-year mark has come and gone, do not panic. Check that you can still feel the implant in your arm by pressing gently along the inner side of your upper arm. If you can feel the rod clearly, removal will almost certainly be straightforward whenever you get to it. If you cannot feel it at all, mention that when you schedule your appointment so the clinic can arrange imaging in advance.

Use backup contraception if you are past five years and pregnancy is not something you want. The data is solid through five years, but beyond that you are in uncharted territory. If you are between three and five years, the evidence supports continued efficacy, but adding a backup method is always a reasonable precaution if the uncertainty bothers you. And if your clinic tells you they cannot discuss extended use or insists on immediate replacement at three years without acknowledging the evidence, you are within your rights to seek a second opinion from a provider who is up to date on the research from the Society of Family Planning and the major clinical trials.