Nociceptive pain is when your body reacts to stimuli like pressure, chemicals, or heat after the stimuli has reached a threshold before it becomes pain. Neuropathic and nociplastic pain do not depend on these triggers. Neuropathic pain comes from damage to the somatosensory nervous system. Nociplastic pain occurs when there’s no clear damage to nerves or tissues. While three types of pain can make nerves more sensitive, peripheral sensitization alone doesn’t explain nociplastic pain. (Image by Nick Ng)The International Association of Pain Society (IASP) have introduced the term “nociplastic pain” in 2017 to describe chronic pain that does not fit into the other two existing pain descriptors: Neuropathic and nociceptive.
However, putting the new term into practice can be challenging since nociplastic pain does not have a specific cause.
In 2025, researchers Dr. Morten Hoegh from the Department of Health Science and Technology at Aalborg University and Dr. Paul Hodges from the School of Health and Rehabilitation Sciences at the University of Queensland wrote in an editorial in JOSPT that meaningful distinctions among all three descriptors “remain unclear,” and their impact on treatment decisions is uncertain.
They wrote that these three descriptors’ commonality is the “engagement of the nociceptive system,” but each of them has different ways to activate.
Hoegh and Hodges defined the three pain descriptors in the following:
Nociceptive pain is “pain that is maintained by ongoing nociceptive input from the tissues.” Such input can be mechanical, chemical, or thermal.
Neuropathic pain is “caused by a lesion or disease of the somatosensory nervous system.” Lesions can be trauma to the brain, and disease is often used for the underlying cause of the lesion, such as diabetes and vasculitis. Somatosensory refers to how the nervous system processes information from within the body, such as internal organs rather than from the body’s external environment.
Nociplastic pain has “no clear evidence of actual or threatened tissue damage” that activates peripheral nociceptors, nor does it have evidence for lesion or disease in the somatosensory nervous system.
They added that patients in chronic pain could have an “overlap” between these mechanisms rather than being boxed in a single one.
“Clinical pain conditions could start out with a dominant nociceptive driver (e.g., tissue injury) but develop features over time that align with nociplastic pain,” they wrote.
The editorial is one out of eight parts of a series of pain science education published in JOSPT that covers the basics of how pain works, such as peripheral and central sensitization, nociception, and bridging pain science to clinical practice. Hoegh said in an interview with Massage & Fitness that there will be a few more in the near future, including a potential topic placebo.
“The series itself is about explaining neuroscience to people who are not neuroscientists, and it’s trying to limit the amount of knowledge that’s actually relevant to understand basic science within the field of pain,” Hoegh said. “We wanted to discuss the three mechanistic descriptors but also pass along some of the vocabulary that we use. For instance, pain mechanisms would refer to something at a molecular level, whereas mechanistic descriptors are ways of looking at pain or a clinical pain condition that has been lasting for more than three months.”
Hoegh said that there is an algorithm—or a step-by-step process like a flowchart—that helps clinicians identify neuropathic pain and guides treatment decisions. However, this algorithm is not as useful for people with nociceptive or nociplastic pain.
“But more importantly, no matter what you end up doing, there are no documented, evidence-based treatments that are superior—meaning that even if you didn’t [use the treatment], you would still be treating the person in front of you, which is the gold standard,” Hoegh said. “And there’s also no assessment that would help you differentiate [the pain]. In the end, however long you spend wondering about whether there’s nociceptive pain or nociplastic pain, you could have spent that time listening to the patient and trying to understand the problem from the patient’s perspective instead.”
Five problems with pain descriptors
Hoegh and Hodges identified five controversies and limitations about using the pain descriptors for clinical use.
Translating animal research to human conditions
They wrote that many animal studies assume that a pain treatment would be effective if the molecular, nociceptive mechanisms in animals were targeted. These studies would test their pain models where nociception is induced with a specific injury (e.g. cutting a sciatic nerve).
“This ignores the complexity and uncertainty of the mix of pain mechanisms in humans,” Hoegh and Hodges wrote. “Differences between species (e.g. how mice, rats and humans behave when in pain), how models of acute pain may not at all be relevant to a lived experience of chronic pain; and how age, gender, context and learning may influence rodents and humans differently.”
Pain mechanisms overlap and there’s no clear distinction
Hoegh and Hodges wrote that there is no consensus or evidence yet that the nociceptive and neuropathic pain “can be discriminated from nociplastic pain, although work is ongoing.” They added that there’s a lack of evidence that links pain descriptors with mechanisms, such as nociplastic pain with central sensitization.
Hoegh said in the interview that central sensitization cannot be directly measured in humans because researchers would have to put needles into specific neurons in people.
“While that can be done…it really doesn’t help us to say that this is or this isn’t a nociceptive neuron,” Hoegh said. “It’s tricky. Even if we could, it would only be the peripheral acting part of it, [like] C fibers and A fibers, because there’s no way we could take a living individual and measure the activity in the dorsal horn [of the spinal cord]. It would expose that individual to massive problems later…so there’s no clinical pain condition that’s relevant.”
Because of the invasive nature of such studies, Hoegh said that researchers turn to alternative ways to study pain, such as using brain scans.
Pain descriptors may only reflect a portion of a person’s pain experience
Hoegh and Hodges wrote that pain is unlikely to be reduced to a single or a combination of pain descriptors, which cannot explain all kinds of pain responses, such as why some people respond well to a treatment when most do not.
“From a clinical perspective, identifying the predominant pain descriptor could inform the [clinician’s] ‘toolbox’ an intervention should come from (e.g., treatments that address the source of nociception for nociceptive pain),” they wrote. “A more detailed understanding of factors such as lifestyle, beliefs, experiences, and socioeconomic status, could help guide tailored care.”
There are no clinical tests to measure nociception and sensitization
Hoegh and Hodges wrote that nociplastic lacks “firm evidence” of underlying mechanisms, unlike nociceptive and neuropathic pain.
“Although one way to disentangle this issue would be to measure sensitization in patients, researchers can only rely on indirect measures, such as clinical signs of allodynia and secondary hyperalgesia to study it,” they wrote.
In this context, allodynia is when a person experiences pain from a stimulus that normally shouldn’t hurt, such as light touch. Secondary hyperalgesia is an area around an injury or sore spot becomes extra sensitive to stimuli that normally would be mildly unpleasant or painful.
Similar in response to item number two above, there is “no way to measure” changes in how nociceptive neurons’ responsiveness in the central nervous system in living humans. Doing so would require recording the neural activity itself.
Using “nociplastic pain” as a placeholder
The term nociplastic pain gives patients a valid explanation when their pain didn’t quite fit the other two pain descriptors, according to Hoegh and Hodges. “However, if pain is considered nociplastic merely by exclusion of the other two descriptors, it will remain a placeholder,” they wrote.
They highlighted that some researchers propose splitting nociplastic pain into two types—top-down and bottom-up—linked to chronic pain, and suggest using clinical algorithms with additional tests to guide individualized treatment. This raises the question of how nociplastic pain differs from “chronic primary pain” with the distinction being that chronic primary pain is defined by its impact on a person’s life, while nociplastic pain is defined by observable abnormal processes in the body.
“A clear and clinically meaningful distinction between all three pain descriptors is not yet achievable. It is unclear whether, and how, treatment will ultimately differ,” they wrote.
Spreading the pain gospel
To disseminate the updated information about pain, Hoegh said that is working on creating a peer-reviewed textbook that tells the full story of the neuroscience field, including pain science. The book would be for graduate students in medicine and related disciplines, and it would also serve as a researcher’s reference.
“I spent over a decade and a half trying to understand what’s necessary to know in neuroscience,” he said. “I’m still trying to convince some of my colleagues who do brain stimulation research to help write another three to four parts [of the pain series]. I want to do one on placebo as well so that we get all these things that people understand are important for pain.”
Meanwhile, Hoegh continues to teach at Aalborg University in Denmark, he also courses planned in Athens (University of Attica in Greece), Amsterdam (via Incitus in Netherlands), and Beirut (Physyour in Lebanon).
You can connect and follow him on LinkedIn.
Email Dr. Morten Hoegh at msh@hst.aau.dk.
Nick Ng, BA
Nick Ng is the editor of Massage & Fitness Jounal and the managing editor for My Neighborhood News Network.
An alumni from San Diego State University with a bachelor’s degree in graphic communications, Nick had completed his massage therapy training at International Professional School of Bodywork in San Diego in 2014. In 2021, he earned an associate’s degree in journalism at Palomar College.
When he gets a chance, he enjoys weightlifting at the gym, salsa dancing, and exploring new areas in the Puget Sound area in Washington state.
