Suggestion to replace PEM by PAR

Deterioration after mental or physical exertion is often referred as “post exertional malaise” (PEM). But the word malaise, is very far from what it is. In the Swedish medical dictionary malaise is defined as a vague diffuse sense of discomfort and tiredness. But the patients rather experience a crash with an increase of most of the symptoms. To be clear that the entire symptom complex deteriorates, it would be better to replace the word “malaise” with “relapse”. Relapse also better describes that it takes some days to recover. Post exertional malaise could be interpreted like a few minutes of feeling slightly unwell after running.

The exertion does not need to feel like an exertion at the time the patient is doing it, and it would be better to replace the word “exertion” with “activity”. So an improved term of “post exertional malaise” (PEM) would be “post activity relapse” (PAR). I think post activity relapse is a far better description, and I hope future disease descriptions, clinical guides and research articles use this terminology. I think post activity relapse is short enough in order to use it several times in a text, without being felt as too burdensome, but I think it is important to clarify somewhere in the text that the activity can be both of mental and physical kind.

The term “relapse after mental or physical activity” has the advantage of being clear that:

  • both physical and mental activity create worsening
  • it must not be an exertion in the classical sense, but rather an activity
  • the worsening does not only create malaise, but a whole range of the ME symptoms are worsened (hyperacusis, ortostatic intolerance, need to rest, cognitive difficulties, pain, etc)
  • it takes days to recover

The relapse does not need to occur directly after the exertion, but it may take a few days (1-3 days, sometimes more) before the deterioration starts. This has been described by Dr John L Whiting from Australia in the message list Co-Cure the 9th of December 2015. For the case there is a delay in the relapse, I suggest that the term “delayed post activity relapse” (DPAR) is used, but that it is also clarified that the activity can be both mental and physical.

Example of use:

A patient with ME must have post activity relapse (PAR), which is a relapse after mental or physical activity. A patient may at occations experience a delayed onset of the PAR, and this is called delayed post activity relapse (DPAR).


Post exertional malaise is proposed to be replaced by “relapse after mental or physical activity”, but for repeated use a shorter form can be used: “post activity relapse” which can be abbreviated “PAR”.

At the occations the onset is delayed the term “relapse with delayed onset after mental or physical activity” is used, but for repeated use a shorter term can be used: “delayed post activity relapse” which can be abbreviated “DPAR”.

4 kommentarer

  1. I used to use, before, like others PwMErs, ” PEM”, but then, the (much realistic and ”better said” terme : PENE come (Post Exhertional Neuro-immune Exhaustion) . I prefer this one from PAR, personnaly

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