Question

I know what it’s like to have post-exertional malaise (PEM) and it’s good to see that PEM is now being recognised by NICE as one of the four key symptoms that are required to make a diagnosis of ME/CFS.

But is PEM unique to ME/CFS? And are there any other medical conditions where people experience PEM?

Answer

Post-exertional malaise (PEM) is the medical term that is used to describe a delayed worsening of symptoms and a decreased ability to function physically or mentally. So it occurs some time later – often by several hours or the following day – after going up to or exceeding individual physical or mental limitations. The worsening is disproportionate to the degree of activity and there is often prolonged recovery time – days or even weeks – before being able to return to normal activity levels.

Although PEM is a very characteristic diagnostic feature of ME/CFS, I don’t think it is unique to ME/CFS. PEM certainly occurs in some people with Long Covid and fibromyalgia. And, when I speak to people with other inflammatory conditions who experience debilitating fatigue and other ME/CFS symptoms, some of them have PEM.

For example, earlier this year I spoke to a group of people with sarcoidosis – an inflammatory condition that often causes debilitating fatigue – about pacing and activity management. After describing PEM in detail it was interesting to find that about a third said they experienced PEM.

So, while PEM is a diagnostic feature of ME/CFS, it may not be unique to ME/CFS.

More Information:

• ME Association Booklet – Pacing: Activity and Energy Management
• ME Association Booklet – Fatigue: The Nature of Fatigue