Some soreness after Nexplanon insertion is completely normal and usually fades within a few days. But if your arm still hurts weeks or months later, or if the pain feels sharp, burning, or radiating, something beyond normal healing may be going on. The cause ranges from minor bruising to nerve irritation, scar tissue formation, or rarely, implant migration.
Normal Pain After Insertion
Right after the implant is placed, the insertion site typically feels numb for two to three hours from the local anesthetic. Once that wears off, you can expect tenderness, mild soreness, and some bruising on your inner arm. This bruising usually clears up within a few days, and the overall soreness should steadily improve over the first week or two.
During this window, it’s normal for the area to feel slightly firm or swollen. You might notice a dull ache when you press on it or bump your arm against something. This is your body’s standard response to a small object being placed under the skin and doesn’t mean anything is wrong. If you’re within the first week or two post-insertion and the pain is mild and gradually getting better, you’re likely on a normal healing track.
Nerve Irritation and Neuropathic Pain
One of the more serious causes of Nexplanon pain is irritation of a nearby nerve, most commonly the ulnar nerve, which runs along the inner arm close to where the implant sits. When the implant presses on or sits too close to this nerve, the sensation is distinct from normal soreness. People describe it as a shooting, searing, or burning pain that radiates from the implant site down toward the elbow or into the ring and pinky fingers.
In a case documented in Cureus, a patient developed constant, unbearable burning pain that worsened when she raised her arm. Even light contact from clothing brushing against the implant site caused significant pain. She also had reduced sensation in her pinky finger and the inner side of her ring finger, which maps exactly to the area served by the ulnar nerve. Touching or pressing on the implant made everything worse.
If your pain has any of these qualities (shooting, electric, burning, or accompanied by numbness or tingling in your fingers), that pattern points to nerve involvement rather than simple tissue soreness. This type of pain doesn’t tend to resolve on its own and needs medical evaluation.
Deep Placement or Improper Positioning
Nexplanon is designed to sit just beneath the skin in a layer of fatty tissue. If it’s placed too deep, closer to muscle or connective tissue, it can irritate surrounding structures and trigger an inflammatory response. The body reacts to the deeper placement with swelling that can compress nearby nerves, producing diffuse pain, tingling, and reactive swelling in the arm.
A key sign of deep placement is that you can’t easily feel the implant when you press on the insertion area. Normally, you should be able to run your finger along your inner arm and feel the thin, rod-shaped implant just under the skin. If it’s not palpable, that’s worth mentioning to your provider, because a non-palpable implant should be located with imaging (ultrasound, X-ray, CT, or MRI) before any removal attempt.
Scar Tissue Buildup
Your body naturally forms a thin capsule of fibrous tissue around the implant as part of its healing process. In most people, this capsule is minimal and doesn’t cause problems. But in some cases, the scar tissue becomes excessive and starts pressing on nearby nerves or creating a painful, firm lump around the implant. This type of pain tends to develop gradually over weeks or months rather than appearing immediately after insertion. It often feels like a localized ache or tightness that doesn’t go away, and it may get worse when you flex or extend your arm.
Infection at the Insertion Site
Any time the skin is broken, bacteria can enter and cause infection. The insertion site is a small puncture wound, so while infection isn’t common, it’s possible. The signs look different from normal post-insertion bruising: increasing redness that spreads outward from the site, warmth to the touch, swelling that gets worse instead of better, and sometimes blisters, skin dimpling, or fluid weeping from the wound.
Normal bruising is purplish and fades over days. An infection gets progressively worse. If you develop a spreading rash around the site along with a fever, that needs urgent medical attention. Even without a fever, redness that’s expanding or a wound that’s oozing should be evaluated within 24 hours.
Allergic or Hypersensitivity Reactions
A small number of people react to the implant materials themselves. Nexplanon contains a hormone (etonogestrel) and barium sulfate, which makes it visible on X-rays. A localized allergic reaction typically shows up within about 48 hours of insertion and looks like redness, noticeable swelling, and itching concentrated around the implant site, without the typical bruising or signs of infection you’d expect from the procedure itself.
Reported rates of insertion-site reactions include redness in about 3.3% of users, bruising-related blood pooling in 3%, general bruising in 2%, pain in 1%, and swelling in less than 1%. A true allergic reaction tends to involve itching as a prominent feature, which sets it apart from normal post-procedure soreness.
Implant Migration
In rare cases, the implant can move from its original position. The most extreme scenario, migration into a blood vessel, occurs in roughly 1.3 per million implants sold worldwide, so it’s exceptionally uncommon. When migration does happen, reported symptoms include unusual bruising or blood pooling at the insertion site and, in the rarest cases involving the vasculature, shortness of breath.
More commonly, an implant may shift slightly within the tissue of the arm. You might notice that the rod feels like it’s in a different spot than where it was placed, or that it’s harder to feel. Any time you can no longer locate the implant by touch, or if you develop new pain in a location that doesn’t match the original insertion site, that warrants imaging to confirm the implant’s position.
Signs That Need Prompt Attention
Most Nexplanon discomfort is temporary and harmless. But certain symptoms signal that something more significant is happening:
- Electric, shooting, or burning pain radiating from the site toward your elbow, hand, or fingers suggests nerve involvement.
- Numbness or tingling in your ring finger, pinky, or along the inner edge of your hand follows the ulnar nerve pathway and points to compression.
- A non-palpable implant (you can’t feel it under the skin) may indicate deep placement or migration and should be imaged.
- Spreading redness, warmth, or oozing from the site suggests infection.
- Persistent pain that worsens over weeks rather than improving is not part of normal healing.
Nerve-related symptoms in particular benefit from early evaluation. The recommended path is imaging to locate the implant, followed by referral to a specialist experienced with peripheral nerves if needed. Early diagnosis leads to better outcomes compared to waiting months to see if the pain resolves on its own.