Nexplanon is not bad for most people who use it. It is one of the most effective contraceptives available, with essentially a 0% failure rate over its approved lifespan, and it carries lower cardiovascular risk than birth control pills. That said, it does come with real side effects and a small number of rare but serious complications worth understanding before you decide whether it’s right for you.
How Well It Works
Nexplanon is a small, flexible rod inserted under the skin of your upper arm that releases a steady dose of a synthetic progestin hormone. It prevents pregnancy by stopping ovulation and thickening cervical mucus. In clinical data submitted to the FDA, there were zero pregnancies among 394 participants tracked over nearly 7,000 at-risk menstrual cycles during an extended use period. That makes it more effective than the pill, the patch, the ring, and even sterilization procedures.
The implant is currently approved for three years of use, and FDA review data show it maintains that 0% pregnancy rate through years four and five as well. Once removed, fertility returns almost immediately. You can get pregnant within days of removal.
Common Side Effects
The most frequent complaint is unpredictable bleeding. Some people experience longer, irregular periods. Others get frequent spotting between periods. And some stop getting periods altogether. These patterns often shift over the first six to twelve months and may settle into something more predictable, but for a significant number of users, irregular bleeding persists for the entire time the implant is in place.
Other commonly reported side effects include headaches, mood changes, weight gain, acne, and breast tenderness. These tend to be mild for most users, but mood-related side effects in particular can be disruptive. Because the implant releases hormones continuously, you can’t simply stop taking it like a pill. Removal requires a minor in-office procedure, which means you’re somewhat committed once it’s placed.
Blood Clot Risk Is Low
One of the biggest safety concerns people have about hormonal birth control is blood clots. Nexplanon performs well here. Combined birth control pills (those containing both estrogen and progestin) raise the risk of venous blood clots roughly 3.5 times above baseline. Nexplanon, which contains only progestin, shows a much smaller signal. One large database study found an adjusted relative risk of just 1.4 compared to nonusers, based on only 5 confirmed clot events over nearly 30,000 person-years of use. A separate case-control study grouped implants with similar progestin-only methods and found no increased risk at all compared to nonusers.
In practical terms, the baseline risk of a blood clot for a young, healthy person is very low, roughly 1 to 5 per 10,000 per year. Nexplanon does not meaningfully change that number for most people. If you have a personal or strong family history of clotting disorders, this is worth discussing with your provider, but for the general population, blood clot risk is not a significant concern with this method.
Implant Migration: Rare but Real
The most alarming complication associated with Nexplanon is migration, where the rod moves from its insertion site and travels through blood vessels, sometimes reaching the lungs. A French nationwide study found the incidence of migration into the pulmonary vasculature was between 1.2 and 3.2 per 100,000 implants sold, depending on the year. That translates to roughly 1 in 30,000 to 1 in 80,000 users.
In 70% of reported cases, the migrated implant ended up in the pulmonary artery or one of its branches. Most cases (59%) were discovered only when a provider attempted to remove the implant and couldn’t find it. About a quarter of cases were flagged because the user had respiratory symptoms like chest pain or shortness of breath, and 17% were caught because the user noticed they could no longer feel the rod under their skin.
This is an extremely rare event, but it’s the reason providers tell you to periodically check that you can feel the implant in your arm. If you can’t locate it by touch, that warrants a visit to get it checked.
Medications That Can Reduce Effectiveness
Certain drugs speed up the liver’s processing of hormones, which can lower the amount of active progestin in your system enough to compromise the implant’s protection. The major categories include some anti-seizure medications, certain antibiotics used for tuberculosis, and the herbal supplement St. John’s Wort. Clinical guidance from the UK’s Faculty of Sexual and Reproductive Healthcare advises against relying on the implant while taking these enzyme-inducing drugs and for 28 days after stopping them.
A few other medications fall into a gray area. Topiramate, used for epilepsy and migraines, may have enzyme-inducing effects even at lower doses, and experts recommend treating it as a potential concern regardless. Lamotrigine, another anti-seizure drug, lacks direct study data on its interaction with the implant, but cautious guidance suggests using backup contraception. If you take any prescription medication regularly, it’s worth confirming there’s no interaction before relying solely on the implant.
Bone Density: An Open Question
Progestin-only injectable birth control (the shot) is known to reduce bone mineral density, especially with long-term use. Whether Nexplanon has a similar effect is less clear. A pilot study published in BMJ Sexual & Reproductive Health found that implant users who stopped getting periods had a higher proportion of low bone density scores than those who continued bleeding, though the results were not statistically significant due to small sample sizes. The study authors raised the possibility that losing your period on the implant could be a marker of lower estrogen levels, which in turn could affect bone health.
Current guidance from clinical bodies states that the evidence is too limited to confirm or rule out a link between implant use and bone density loss. This is different from saying there’s no effect. It means we don’t have enough data yet. For most users in their reproductive years, this is unlikely to be a practical concern, but it may matter more for people with existing risk factors for osteoporosis or those planning very long-term use.
Who Should Avoid It
The CDC classifies current breast cancer as the primary condition that rules out implant use. People with active breast cancer should not use Nexplanon. Beyond that, the implant has remarkably few absolute contraindications compared to combined hormonal methods. It’s considered safe for people with high blood pressure, migraines with aura, obesity, and a history of blood clots, all of which are red flags for estrogen-containing contraceptives.
For the average user without breast cancer or significant drug interactions, Nexplanon carries a favorable safety profile. The most common reasons people have it removed early are bleeding irregularities and mood changes, not dangerous complications. Whether those side effects feel “bad” depends entirely on your experience with them, and there’s no reliable way to predict how your body will respond before trying it.