Fibromyalgia is associated with nociplastic pain, a type of pain that originates from changes in how the central nervous system processes pain signals rather than from tissue damage or nerve injury. This makes it fundamentally different from the pain of a broken bone, a surgical wound, or a pinched nerve. The pain is widespread, chronic, and real, but it stems from the brain and spinal cord amplifying sensory input rather than from an injury site sending alarm signals.
Why Fibromyalgia Pain Feels Different
Pain generally falls into three categories. Nociceptive pain comes from actual tissue damage, like a sprained ankle or a burn. Neuropathic pain results from damage to the nerves themselves, as in diabetic neuropathy or sciatica. Nociplastic pain, the category fibromyalgia belongs to, involves neither. Instead, the nervous system’s pain-processing machinery has become overly sensitive, turning up the volume on signals that wouldn’t normally register as painful.
Brain imaging studies show that people with fibromyalgia have greater activation in the brain’s pain-processing regions compared to healthy controls. Their brains also show increased connectivity between pain-processing areas and the brain network that’s active during rest, which may explain why pain can feel present even without any physical stimulus. At the same time, the system that normally dials pain signals back down (the descending pain-modulating system) shows decreased activity. The result is a nervous system stuck in a state of heightened alert: signals get amplified on the way up and aren’t dampened on the way down.
Cerebrospinal fluid studies reinforce this picture. People with fibromyalgia have elevated levels of excitatory chemical messengers, including substance P and glutamate, both of which make neurons more reactive to incoming signals.
What the Pain Actually Feels Like
The hallmark of fibromyalgia is chronic widespread pain, meaning it occurs on both sides of the body, above and below the waist, and along the spine. Patients most commonly describe musculoskeletal pain, generalized aching, and deep fatigue that accompanies the pain. The sensation can shift in character and location from day to day.
Two specific pain phenomena are especially common. Allodynia is pain from something that shouldn’t hurt at all, like the light pressure of clothing against your skin, a gentle touch, or a seat belt across your chest. Hyperalgesia is an exaggerated pain response to something that would normally cause only mild discomfort, like a firm handshake or bumping your arm on a doorframe. Both frequently coexist in fibromyalgia, and both reflect the same underlying problem: the nervous system interpreting ordinary sensory input as threatening.
Pressure pain testing illustrates this clearly. In one study, people with fibromyalgia registered pain at forearm pressure levels of about 4.2 units, while healthy controls didn’t feel pain until roughly 7.6 units of pressure were applied. At the trapezius muscle (the large muscle between neck and shoulder), the threshold was 6.9 for fibromyalgia patients versus 10.7 for controls. Their nervous systems simply flag sensation as painful much sooner.
Daily Pain Patterns and Flare Triggers
Fibromyalgia pain tends to come and go in waves. Many people experience morning stiffness that typically lasts less than an hour, with pain intensity fluctuating throughout the day. There are periods of heightened symptoms (flares) followed by stretches where pain is milder or even temporarily absent.
Several factors can trigger or intensify flares. Stress is one of the strongest. In a study tracking fibromyalgia patients alongside daily weather data, stress was the single most powerful predictor of pain intensity on any given day. Weather also played a role: drops in barometric pressure and increases in humidity were both linked to higher pain levels. Interestingly, stress didn’t just add to weather-related pain. It amplified it. When barometric pressure dropped, patients with higher stress levels experienced a significantly greater spike in pain than those with lower stress, suggesting the two triggers compound each other. Temperature alone showed no significant effect.
Tender Points vs. Trigger Points
For decades, fibromyalgia was diagnosed by pressing on 18 specific “tender points” around the body. These are areas of tenderness in muscles, tendons, and soft tissue that hurt when pressed but don’t refer pain elsewhere. This is different from “trigger points,” which are tight bands within muscle that produce a predictable pattern of pain radiating to other areas. Trigger points are characteristic of myofascial pain syndrome, a regional pain condition. Tender points in fibromyalgia are more widespread. The two can overlap, and some people have both conditions simultaneously.
Current diagnostic criteria no longer require a physical tender point exam. Instead, clinicians use two scales: one measuring how many body regions are painful (the Widespread Pain Index) and another measuring symptom severity, including fatigue, sleep quality, and cognitive difficulties. A diagnosis requires either widespread pain across seven or more regions with moderate symptom severity, or pain in four to six regions with high symptom severity.
Pain That Travels With Other Conditions
Fibromyalgia rarely shows up alone. A large population-based study found that people with chronic widespread pain had dramatically elevated odds of also experiencing chronic fatigue (over 23 times more likely than the general population), joint pain (about 7 times more likely), depressive symptoms (about 5 times more likely), and irritable bowel syndrome (about 5 times more likely). Temporomandibular joint disorder (jaw pain) and heightened sensitivity to chemicals are also common companions.
These overlapping conditions aren’t coincidental. Many of them share the same underlying mechanism of central sensitization, where the nervous system becomes broadly hypersensitive. This is why fibromyalgia often involves not just pain but also heightened sensitivity to light, sound, and temperature, along with gut symptoms and cognitive fog. The pain is one expression of a nervous system that has shifted into a persistently reactive state.