How Is Nociplastic Pain Diagnosed After Other Causes?

Assessing nociplastic pain is a careful clinical process rather than something confirmed by a single scan or blood test ^[1]. Doctors are not trying to prove that nothing else is wrong, nor are they just ruling things out. Instead, they evaluate whether your pain distribution, intensity, and accompanying symptoms can be fully explained by other primary mechanisms ^[2].

To do this, clinicians look at three main categories:

1. Nociceptive pain: Pain arising from actual or threatened damage to non-nerve tissue, such as a joint, bone, or muscle ^[2].
2. Neuropathic pain: Pain caused by a lesion or disease of the somatosensory nervous system (the system that processes touch and pain) ^[2].
3. Nociplastic pain: Pain that arises from altered nociception (pain processing) despite no clear evidence of actual tissue damage or nerve disease causing it ^[3].

If your symptoms are not fully explained by the tissue or nerve findings identified so far, doctors will consider whether altered nociception is contributing to your pain ^[4].

Important Warning Signs (Red Flags)

While chronic pain is generally assessed through scheduled clinical appointments, certain symptoms require prompt or emergency medical attention. Seek urgent evaluation if you experience your pain alongside any of the following:

• New or progressive muscle weakness
• New bowel or bladder dysfunction, or numbness in the groin/saddle area
• Severe pain accompanied by a fever, chills, or feeling acutely unwell
• Unexplained weight loss or a recent history of cancer
• Pain resulting from major trauma (like a fall or car accident)

The Role of Your Medical History

The first step in assessing your pain is a detailed conversation. According to established clinical criteria for musculoskeletal pain, features that support a possible nociplastic pain presentation include:

• Pain lasting longer than 3 months ^[4].
• A regional, multifocal, or widespread distribution, rather than pain confined to a single discrete structure ^[4].
• Pain that is not entirely explained by nociceptive or neuropathic mechanisms ^[4].
• Clinical signs of hypersensitivity in the affected region ^[4].

Patients with “probable” nociplastic pain may also experience generalized symptoms, such as extreme fatigue, unrefreshing sleep, or cognitive difficulties (“brain fog”) ^[5]. They may also show allodynia (feeling severe pain from things that shouldn’t hurt, like a light touch) or hyperalgesia (an exaggerated response to mildly painful stimuli) ^[6]. However, not every patient has all of these symptoms, and no single symptom diagnoses nociplastic pain on its own.

Physical and Neurological Examinations

A hands-on examination helps your doctor distinguish between different pain mechanisms.

To look for nociceptive pain, the doctor will check your joints and tissues for visible swelling, warmth, redness, or restricted movement ^[7]. To evaluate for neuropathic pain, they will perform a neurological exam, checking for sensory deficits (numbness), muscle weakness, or reflex asymmetry in a specific distribution that matches known nerve pathways ^[8].

If your exam shows diffuse tenderness or widespread hypersensitivity without localized joint swelling or specific nerve deficits, this is consistent with a nociplastic pain phenotype (observable clinical presentation) ^[6]. However, this does not definitively establish nociplastic pain or exclude other diseases. Inflammatory disease can sometimes cause very little visible swelling, and some neuropathic conditions can present with a normal routine neurological exam ^[9][10].

When Are Targeted Tests Needed?

There is no specific biomarker or definitive test for nociplastic pain ^[1]. Instead, laboratory tests and scans are ordered selectively based on your symptoms to investigate suspected alternative or coexisting conditions ^[11]. A “blanket” testing panel is rarely helpful.

Blood Tests

Blood tests are used to check for systemic (body-wide) inflammation, autoimmune disorders, or metabolic issues. If you have widespread pain resembling fibromyalgia, a doctor might order a limited initial panel including a complete blood count (CBC), markers of inflammation like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), and a thyroid-stimulating hormone (TSH) test ^[7].

What a normal test does—and does not—mean: Normal blood tests can lower the suspicion for certain conditions, but they do not prove you have nociplastic pain, nor do they completely rule out all autoimmune illnesses ^[12]. Results must always be interpreted alongside your history and physical exam.

Imaging Studies (X-Rays, MRIs)

Imaging is used to look for secondary causes like fractures, tumors, or severe arthritis ^[13]. However, imaging abnormalities must be interpreted carefully. Common age-related or degenerative findings are very frequent on scans, even in people without pain ^[13]. Therefore, an abnormal finding on an MRI might just be an incidental finding (something that is there but not causing the problem). An abnormality does not automatically mean it is the source of your severe pain, nor does it rule out nociplastic pain ^[14].

Nerve Tests: EMG and NCS

Electromyography (EMG) and nerve conduction studies (NCS) measure electrical activity in your nerves and muscles. These tests are primarily ordered if your doctor suspects an atypical focal nerve disorder, radiculopathy (a pinched nerve in the spine), or a trapped nerve ^[15][16].

A normal routine EMG/NCS does not rule out all nerve issues. These tests mainly assess large nerve fibers and may miss small-fiber neuropathy (damage to the tiny nerve endings in the skin) ^[10]. If small-fiber neuropathy is suspected, a specialist evaluation may use clinical findings, autonomic testing, or a skin biopsy ^[10]. Conversely, electrodiagnostic testing alone cannot confirm or exclude nociplastic pain ^[17].

Coexisting Pain: You Can Have More Than One Type

Historically, doctors believed that to diagnose nociplastic pain, they had to completely rule out all other types of pain. Medical understanding has evolved, and experts now recognize that nociceptive, neuropathic, and nociplastic pain mechanisms can—and often do—coexist ^[18][19].

For example, a person might have nociceptive pain from osteoarthritis in their knee, but also develop altered nociception resulting in widespread nociplastic pain ^[3]. Having an autoimmune disease or a nerve injury does not mean you cannot also have nociplastic pain ^[12]. The goal of the diagnostic process is not to force your symptoms into a single category, but to identify all the active pain mechanisms so that your treatment plan can address them comprehensively ^[20][4].