Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regards to family planning.
Nexplanon is a birth control treatment for women that’s implanted in the arm and lasts for 3 years. The manufacturer claims it’s as effective as the pill, and easily reversible by removing the implant if the woman wants to get pregnant.
In this article we’ll review the medical research on Nexplanon, highlight its side effects, and compare its efficacy to other popular forms of birth control.
Does Nexplanon Work?
An extensive systematic review was published in 2021 in the Reproductive Health journal examining the efficacy of Nexplanon.
The researchers found that among the studies reviewed, the rate of unintended pregnancy while using Nexplanon ranged from 0 to 1.4 unintended pregnancies per 100 years used. This is an extremely high level of efficacy, and makes Nexplanon a good option for birth control.
Another recent medical review confirmed these results, and the study authors even wrote that Nexplanon and its class of medical devices are the most effective form of birth control on the market.
We can conclude that Nexplanon is effective, given that the two linked meta-studies each reviewed tens of individual clinical trials on the device. It’s also worth noting that the Food and Drug Administration (FDA) in the U.S. wouldn’t approve Nexplanon as a medical device if it wasn’t proven to be effective on average.
How Does Nexplanon Work?
Nexplanon is a device inserted into the arm, so it requires a prescription and a clinic visit. It contains 68 milligrams (mg) of etonogestrel, which is released throughout the day and circulates in the body.
Etonogestrel is a synthetic progestin molecule, meaning it’s chemically similar to the hormone that regulates pregnancy and menstruation in women. This is the only active ingredient in Nexplanon and is what makes it so effective.
Nexplanon causes etonogestrel levels in the body to remain around 200 picograms (pg) per millimeter (mL), which is well above the 90 pg/mL level which prevents ovulation, according to this medical review of a device with the exact same active ingredient and dosage marketed under a different name.
Because Nexplanon’s efficacy involves continually circulating etonogestrel, its effects are transient and conception is possible if the woman chooses to remove the device with the help of a doctor.
Nexplanon Side Effects
The previously linked review of the efficacy of Nexplanon also documented its side effects by percentage of patients affected.
Amenorrhea, which is the medical term for a missed period, was the most common side effect, with 41% of patients experiencing this. Infrequent bleeding and frequent bleeding affected 24% and 18% of women in the trial respectively.
The two most notable non-menstrual side effects were breast tenderness (19%) and acne (10%).
The side effects page on Nexplanon’s official website explains that 1 in 10 women in their clinical trials stopped using the treatment due to unfavorable changes in their menstrual bleeding pattern.
Nexplanon notably does not have a black box warning on their label, which is an FDA requirement for prescription products that have serious safety risks. This is a good sign in terms of patient risk.
The increased bleeding risks caused by Nexplanon are significantly higher than the increased bleeding risks from copper IUD Paragard, as shown in the medical research from the linked review.
Nexplanon Removal Risk
The risk of complications from insertion and removal of the Nexplanon device provides an additional risk vector to the side effects from the drug itself.
A recent medical review published in the well-respected Contraceptive journal examined real-world data on Nexplanon procedure issues. The researchers found that incorrect insertion of the device affected 12.6 patients per 1,000 insertions, and that the most common side effect was the sensation of pins and needles or numbness in the arm that the device was inserted into.
Occasionally the implant had become encased in fibrotic tissue upon removal.
None of the insertion and removal events caused serious adverse effects, even in the rare cases of practitioner error.
Nexplanon Vs. Other Birth Control Methods
One of the most important considerations for a patient evaluating birth control options is their relative efficacy. Thankfully, there have been population studies directly comparing the rate of unplanned pregnancy between different forms of contraception.
A medical review on preventing unintended pregnancy published in the Journal of Women’s Health found that in real-world use cases, Long-Acting Reversible Contraceptive (LARC) methods such as Nexplanon were 20x more effective than non-LARC methods such as the pill or condom use.
This is mostly due to human error: with implanted devices like Nexplanon, there is no vector for human error that can affect the risk of unintended pregnancy. But for physical barriers like the condom, they can be used incorrectly or patients may even forget to or choose not to use them, which greatly increases pregnancy risk.
Since LARC methods are proven to be the most effective for birth control, it’s useful to compare Nexplanon with other LARC methods like copper IUD Paragard.
Nexplanon appears to be slightly more effective than Paragard at preventing unintended pregnancy. The failure rate of Paragard ranges from 0.3% to 0.6% over its 5 year lifespan as documented by medical studies.
Our review of medical literature on Nexplanon in the first section showed a failure rate range of 0 - 1.4 unintended pregnancies per 100 years, which would correspond to an upper-range failure rate of 0.07% over 5 years.
How Long Does Nexplanon Last?
Nexplanon is approved for use by the FDA up to 3 years, and this is its typical use duration. After 3 years, the device is typically removed and a new device is re-inserted if the woman chooses to continue with the therapy.
A clinical trial examined extended use of Nexplanon, and found that using it for 5 years rather than 3 didn’t increase pregnancy risk. No pregnancies occurred during the additional 2 years.
Patients who lost health insurance or who cannot afford new treatment may want to speak to their doctor about extended use of Nexplanon given that it’s proven effective in at least one medical study, but we don’t recommend off-label use of medical devices.
Does Nexplanon Cause Weight Gain?
While there are some consumer reports of weight gain amongst Nexplanon users, the clinical reviews cited in this article which analyzed a host of side effects did not document weight gain on average compared to control groups.
Weight is affected by many factors, and often patients misattribute it to one new therapy. In the case of Nexplanon, there doesn’t appear to be clinical evidence that it causes weight gain on average.
One clinical trial did document weight gain in a specific subset of Nexplanon users. Women with genetic variants at Estrogen Receptor 1 (ESR1) gained a significant amount of weight while on the therapy. This group gained 14.1 kilograms on average, which equates to 31.1 pounds.
Women who have completed a genetic analysis using a service such as 23andMe may want to discuss the results with their doctor prior to considering Nexplanon use, to rule out if they’re in that potentially higher-risk group for weight gain.