Note: See also the page on Fibromyalgia. Many patients with ME/CFS also have Fibromyalgia.

Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) is a complex chronic illness affecting multiple body systems. People with ME/CFS experience a diverse array of symptoms involving the immune, nervous, endocrine and autonomic systems. They also experience a profound decrease in energy levels that seriously impairs their ability to function at a normal capacity.

Post Exertional Malaise

A hallmark symptom is post exertional malaise (PEM). Patients experience an exaggeration of symptoms following physical or mental exertional. Over-activity can provoke symptoms like pain, cognitive impairment and exhaustion. This response is referred to as a "crash". PEM can occur immediately or can be delayed for hours or days. Recovery time varies a great deal. For some, doing ordinary things like attending a social event could leave them bedridden for days.

Orthostatic Intolerance

Many patients with ME/CFS have Orthostatic Intolerance. They experience an onset of symptoms while standing or being upright for a prolonged period of time. Two forms of OI are neurally mediated hypotension (NMH) and postural tachycardia syndrome (POTS). These conditions are well descibed in an artils by Dr. Peter Rowe: GENERAL INFORMATION BROCHURE ON ORTHOSTATIC INTOLERANCE AND ITS TREATMENT

Severity

The level of impairment varies among patients. All patients experience a significant reduction in their pre-illness functioning levels. Some are able to manage in a reduced capacity by cutting back on activities and managing their daily tasks through pacing. Many are homebound much of the time. Severely ill patients are bedbound unable to do basic tasks like getting dressed or even sitting up.

The burden of illness is compounded by the many symptoms that can accompany the illness. Sleep is impaired and food and drug sensitivities are common.

Onset

Onset can occur suddenly or it can be gradual. Many patients can pinpoint the start of their illness following a severe infection or trauma.

Prevalance

ME/CFS affects men and women of all ages. According to the Canadian Community Health Survey of 2014, 407,600 Canadians were diagnosed with Chronic Fatigue Syndrome.