What illnesses cause PEM?
                                
                                
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                                    5 min read                                
                            
                                Post-Exertional Malaise (PEM) is a hallmark symptom of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), but it is also a feature of several other chronic conditions. This debilitating worsening of symptoms, triggered by minimal physical or cognitive effort, can significantly impact a person's daily life.