Pain at your Nexplanon site months after insertion is not a normal part of the healing process. The initial soreness from the insertion procedure typically fades within a week or two, so pain that shows up later, or never fully went away, usually points to a specific cause: the implant’s position relative to nearby nerves, scar tissue forming around the rod, or the implant shifting from its original location.
Nerve Contact or Compression
The most common explanation for persistent or delayed pain is that the implant is sitting on or near a nerve. The inner upper arm, where Nexplanon is placed, contains several superficial nerves, and even a tiny rod can cause problems if it presses against one. The medial cutaneous nerve of the forearm runs through this area, and case reports have documented patients developing pain, numbness, and tingling from direct contact between the implant and this nerve. One published case described a patient with a two-year history of pain and abnormal sensations along the inner forearm, all traced back to the implant resting against that nerve.
If the implant was placed too close to the elbow, the ulnar nerve is also at risk. This is the nerve responsible for the “funny bone” sensation, and it runs close to the surface in that area. Compression here can cause tingling or numbness that radiates into the ring and pinky fingers.
What makes nerve-related pain confusing is that it doesn’t always start right away. Repeated small movements of the arm, gradual tissue changes, or minor shifts in the implant’s position can bring it into closer contact with a nerve over weeks or months. The pain might feel like aching, burning, or a shooting sensation. You might also notice numbness or a pins-and-needles feeling that extends beyond the implant site, sometimes reaching the hand or fingers.
The Implant May Have Moved
Nexplanon is designed to stay in place just beneath the skin, about 7 centimeters above the elbow crease, in the groove between the biceps and triceps. When placed correctly, it sits no more than about 1 centimeter deep. But implants can migrate from their original position, and it’s often unclear whether that movement happened during insertion or gradually over time.
Migration can bring the rod into contact with structures it wasn’t near initially, including nerves, muscle tissue, or the tough connective tissue (fascia) that wraps around muscles. If the implant moves deeper into the arm or shifts along its length, you may notice new pain or tenderness in a spot that wasn’t sore before. In rare and extreme cases, implants have traveled far from the arm entirely, but localized migration within the upper arm is the more relevant concern for most people experiencing new discomfort.
One clue that your implant may have moved: you can no longer feel it as easily under the skin, or it seems to be in a different spot than where you remember it being placed.
Scar Tissue and Inflammation
Your body treats the implant as a foreign object. Over time, it builds a thin capsule of fibrous tissue around the rod. This is a normal immune response, but in some people the capsule becomes thick enough or tight enough to create pressure on surrounding tissue. This process doesn’t happen overnight. It can take weeks to months to develop, which is why you might feel fine initially and then notice a dull ache or tenderness developing later.
The scar tissue itself isn’t dangerous, but if it forms in a way that presses the implant more firmly against a nerve or pulls on nearby tissue, it can produce persistent soreness or sensitivity at the site. Some people describe it as a deep ache that worsens with certain arm movements, especially when the muscle contracts around the implant.
Deeper Placement Causes More Problems
The implant is meant to sit in the fatty layer just beneath the skin, not in or below the muscle. When it ends up deeper than intended, it’s more likely to interact with nerves, blood vessels, and muscle fibers. A deeper placement also makes it harder to feel the implant through the skin, which means you might not notice early signs of movement.
People with less subcutaneous fat on the inner arm are at higher risk for deeper placement, simply because there’s less tissue between the skin surface and the muscle layer. If your pain feels muscular, worsens with specific arm movements like lifting or twisting, or seems to come from deep within the arm rather than near the surface, the implant may be sitting deeper than it should.
What Pain Resolution Looks Like After Removal
For most people whose pain is caused by the implant’s position, removal resolves the problem. Data from older implantable devices shows that nerve-related tingling and pain typically go away once the rod is taken out. However, the longer a nerve has been compressed or irritated, the longer recovery can take.
In rare cases where an actual nerve injury has occurred (not just compression but damage to the nerve fibers), recovery is less predictable. One documented case of ulnar nerve injury required surgical nerve reconstruction, and seven months later the patient still had significant numbness and only weak muscle function in the affected hand. These severe outcomes are uncommon, but they underscore why persistent neurological symptoms shouldn’t be ignored for months on end.
Symptoms That Need Prompt Attention
Some types of arm pain after Nexplanon are worth monitoring. Others need faster action. The manufacturer’s own guidance lists weakness or numbness in your arm or leg as a reason to contact your healthcare provider immediately. Specific warning signs to watch for include:
- Progressive numbness that spreads beyond the implant site, especially into the hand or fingers
- Muscle weakness in the hand or forearm, like difficulty gripping objects
- Tingling or burning that follows a consistent path down the arm
- Pain that worsens steadily over weeks rather than staying stable or improving
- Inability to feel the implant under the skin when you could before
A dull ache that comes and goes with arm movement is worth bringing up at your next appointment. Numbness, weakness, or spreading nerve pain is worth calling about sooner. The distinction matters because nerve compression that’s caught early can resolve completely with removal, while prolonged compression raises the risk of lasting damage.