Nexplanon is not an IUD. It’s a small hormonal implant that goes under the skin of your upper arm, while an IUD is a T-shaped device placed inside the uterus. The two get confused because they belong to the same category of birth control, called long-acting reversible contraception (LARC), and they share some similarities: both last for years, both are over 99% effective, and both can be removed whenever you want. But they are physically different devices that work in different parts of the body.
What Nexplanon Actually Is
Nexplanon is a soft, flexible rod about the size of a matchstick, 4 cm long and 2 mm wide. The FDA classifies it as a “radiopaque subdermal implant,” meaning it sits just beneath the skin and can be seen on an X-ray. It releases a synthetic progestin hormone that prevents pregnancy in three ways: it stops ovulation, thickens cervical mucus so sperm can’t easily reach an egg, and changes the uterine lining to make implantation less likely.
The implant is approved for three years of continuous use. During that time, it has a failure rate of essentially zero in clinical trials, making it one of the most effective contraceptives available.
How IUDs Differ
An IUD is a tiny T-shaped device that a provider inserts through the cervix and into the uterus using a specialized tool. There are two types: hormonal IUDs (like Mirena, Kyleena, and Liletta) that release a progestin locally inside the uterus, and copper IUDs (like Paragard) that contain no hormones at all. Depending on the type, IUDs last anywhere from three to twelve years.
The key physical distinction is location. Nexplanon sits in your arm. An IUD sits in your uterus. This difference affects the insertion experience, the side effects you’re likely to notice, and how each method delivers its contraceptive effect.
Why People Confuse Them
Both Nexplanon and IUDs fall under the LARC umbrella, which the American College of Obstetricians and Gynecologists describes as the most effective forms of reversible birth control. LARC methods are about 20 times more effective than the pill, the patch, or the ring over time. Because doctors often discuss implants and IUDs together during contraceptive counseling, many people leave those conversations thinking they’re variations of the same thing.
They’re not. The FDA’s own labeling for Nexplanon lists “implants” and “intrauterine devices” as separate categories in its birth control effectiveness charts. When the label gives instructions for switching methods, it treats them as distinct.
What Insertion Feels Like for Each
Getting Nexplanon placed takes a few minutes. Your provider numbs a small area on the inside of your upper arm, then uses a preloaded applicator to slide the rod under the skin. You’ll get an adhesive bandage and a pressure bandage to reduce swelling and bruising. Some soreness and bruising at the site is normal for a few days, and over-the-counter pain medication or an ice pack is usually enough to manage it. The implant can also be placed right after giving birth.
IUD insertion is a different experience. A provider guides the device through your cervix, which can cause cramping that ranges from mild to intense. Some people feel fine within minutes, while others have cramps for a day or two afterward. Neither procedure requires anesthesia, though both involve some level of temporary discomfort in different parts of the body.
Side Effects Compared
Because Nexplanon releases hormones into your bloodstream from your arm, its side effects tend to be more systemic. Based on user-reported data, the most commonly noted effects include weight gain (about 31% of users), irregular bleeding (28%), mood swings (27%), depression (23%), and acne (21%). Anxiety was reported by roughly 14% of users.
Hormonal IUDs like Mirena release progestin directly inside the uterus, so a smaller amount enters the bloodstream. Their most common user-reported effects skew more toward local symptoms: cramping (about 46% of users), bleeding (30%), and spotting (23%). Systemic effects like weight gain (18%), acne (14%), and mood swings (10%) still occur but are reported less frequently than with Nexplanon.
Copper IUDs have no hormonal side effects at all, but they commonly cause heavier periods and stronger cramps, especially in the first few months.
Effectiveness Is Nearly Identical
Both methods have failure rates below 1% per year, and large studies have found that this holds true regardless of body weight. In clinical trials, the implant’s failure rate was actually 0.00 per 100 women-years of use. IUDs come in just slightly behind, but the difference is so small that both are considered equally reliable in practice. If choosing between the two, effectiveness alone won’t help you decide.
Choosing Between Them
The decision usually comes down to where you’re comfortable having a device, how you feel about hormonal side effects, and how long you want coverage. Nexplanon lasts three years and requires a small arm procedure. Hormonal IUDs last three to eight years depending on the brand, and the copper IUD lasts up to twelve. If you want to avoid systemic hormones entirely, the copper IUD is the only LARC option that allows that.
Some people prefer the implant because they can feel it in their arm and confirm it’s still in place. Others prefer an IUD because it’s out of sight and, in the case of hormonal versions, delivers hormones locally with fewer whole-body effects. Both are removed easily by a trained provider whenever you’re ready, and fertility returns quickly after removal with either method.