Pain Threshold and Pain Tolerance in Fibromyalgia

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They’re Not the Same!

Pain threshold

There is a huge misconception that still exists when it comes to understanding the degree of pain people with Fibromyalgia experience. The reason for this confusion is that there are actually two separate terms used to describe levels of pain.

The term “pain threshold” defines the level at which the body first perceives a stimuli as being painful. The term “pain tolerance” has a completely different meaning and basically defines how much pain a person can actually take without breaking. We can think of tolerance as the “acceptance level” of an existing pain.

Fibromyalgia have a low threshold and most often a very high tolerance to pain

People that suffer with Fibromyalgia have a low threshold and most often a very high tolerance to pain. This is partly true because they have been found to have greatly increased levels of substance P in the cerebral spinal fluid. Substance P is a neuromodulator (a substance that changes neurotransmitter effectiveness) that allows us to perceive a stimulus as painful.

It is interesting to mention that there are actually some rare medical conditions where substance P is very low or completely absent and a person feels little or no pain. That may initially seem like a blessing but actually it can be very dangerous because there is then no “warning pain” when a critical condition requiring treatment exists in the body. Can you imagine how serious it would be for someone with acute appendicitis to not feel any pain and have the appendix rupture?


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Pain Thresholds and Fibromyalgia

Pain thresholds vary from person to person and research suggests that they are abnormally low in fibromyalgia. That’s why things that aren’t painful to most people can cause pain in those with this condition. The medical term for pain caused by things that don’t normally hurt is allodynia. In fibromyalgia, the pressure pain threshold (the point at which pressure becomes painful) is a common area of focus for researchers.

A low-pressure pain threshold is the reason behind the tender-point exam, which is a common diagnostic method for the condition. Two studies have looked at whether doctors can use a blood pressure cuff as a simple way to identify patients who should be evaluated for fibromyalgia. Both concluded that it’s a reasonably accurate way to identify a low pressure-pain threshold.

Effects of exposure to pain

“It is widely believed that regular exposure to painful stimuli will increase pain tolerance – i.e. increase the ability of the individual to handle pain by becoming more conditioned to it. However, this is not true the greater exposure to pain will result in more painful future exposures. Repeated exposure bombards pain synapses with repetitive input, increasing their responsiveness to later stimuli, through a process similar to learning. 

Therefore, although the individual may learn cognitive methods of coping with pain, these methods may not be sufficient to cope with the boosted response to future painful stimuli. “An intense barrage of painful stimuli potentiates the cells responsive to pain so that they respond more vigorously to minor stimulation in the future.

Which leads to pain sensitization “central sensitization where nociceptive neurons in the dorsal horns of the spinal cord become sensitized by peripheral tissue damage or inflammation, this type of sensitization has been suggested as a possible causal mechanism for chronic pain conditions?

Role of normal levels of substance P

Obviously having a normal level of substance P is the ideal situation where your body tells you exactly what it should be feeling and pain is perceived at the appropriate level. Take a look at the illustration below and you will get a general idea how Substance P works.

You can see that the transmission of nerve impulses and pain is quite intricate and involves many more chemicals but Substance P plays a very important role. Now with elevation of Substance P, as in Fibromyalgia, a sensation that should be perceived as normal is felt as painful.

The term for this condition of increased pain perception is hypergesia. Sometimes even a light touch on the skin can feel like burning and I have seen many patients that can’t even stand to have the bed sheets touch their legs at night. In Fibro patients a relatively minor muscle strain due to over exertion will often cause a totally inappropriate severe level of pain and then cause unnecessary muscle splinting and spasm which then has a downward spiraling effect.

The body over responds due to an inaccurate pain signal caused by high substance P and starts what I call the “cascading of symptoms”. One simple strain becomes a serious of pains that can sometimes throw the Fibro patient into a severe flare.

Pain threshold and pain tolerance in fibromyalgia patients

Pressure pain thresholds and pressure pain tolerances on non-trigger-point muscle and bone were measured with a dolorimeter in 46 female patients with primary fibromyalgia and in 50 healthy women of the same age. The pressure pain thresholds and the pressure pain tolerances on both muscle and bone were lower in the fibromyalgia patients than in the healthy controls.

All the differences were statistically highly significant, though there was a certain degree of overlapping between the patients and the controls. It is concluded that patients with primary fibromyalgia have a generalized amplification of pain sensitivity, a sign that might be useful in the diagnosis of fibromyalgia.

So does this mean that Fibro patients are weak? Does it mean that we are just being hysterical with the pain and over reacting? No, actually it is usually the complete opposite. Here is where the definitions of threshold vs. tolerance become very important. Fibro patients do feel pain sooner and at inappropriate levels but, for most of us, we have incredibly high pain tolerances. The reason for this is because Fibro patients deal with some level of pain all the time.


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  • Chandran AB, et al. Nursing research. 2012 Sep-Oct;61(5):363-8. Sphygmomanometry-evoked allodynia in chronic pain patients with and without fibromyalgia.
  • Meeus M, et al. Journal of rehabilitation medicine. 2010 Oct;42(9):884-90. Reduced pressure pain thresholds in response to exercise in chronic fatigue syndrome but not in chronic low back pain: an experimental study.
  • Winger A, et al. BMJ open. 2014 Oct 6;4(9):e005920. Pain and pressure pain thresholds in adolescents with chronic fatigue syndrome and healthy controls: a cross-sectional study.
  • Zanette SA, et al. Molecular pain. 2014 Jul 8;10:46. Higher serum S100B and BDNF levels are correlated with a lower pressure-pain threshold in fibromyalgia.
  • Pain Threshold and Pain Tolerance in Fibromyalgia & ME/CFS by Adriene Dellwo via Verywell Health

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