ME/CFS is a complex physical disease which affects many parts of the body and therefore causes a variety of symptoms.
ME/CFS is characterised by post-exertional malaise. This is a worsening of fatigue and other symptoms after even mild physical or mental effort, which may be delayed by hours or days, and which is not improved by rest.
The intense fatigue associated with ME/CFS is far more severe than the normal fatigue experienced by healthy people after exertion.
People with ME/CFS can also experience many other symptoms that have a significant impact on their lives, including muscle or joint pain, stomach or intestinal problems, difficulty sleeping, memory or concentration problems, headaches, sore throat, and difficulties with vision.
Different people experience different combinations of symptoms; this is known as disease heterogeneity. Symptoms can vary in severity between individuals, and over time in the same individual. The length of time that someone may be affected by ME/CFS also varies a lot from person to person.
The underlying cause of ME/CFS is not yet known, although many individuals report getting the disease after a viral infection. There is also no specific laboratory test for the disease, and diagnosis is currently based on a person’s medical history and pattern of symptoms, and by ruling out other illnesses.
However, research (including that supported by ME Research UK) has identified many biological differences between people with ME/CFS and healthy individuals. These support the physical nature of the disease, and will hopefully lead to a cause being found, and to the development of diagnostic tests and ultimately a cure.
There are not yet any treatments for ME/CFS. Some people find that managing their activity can help them live with the illness, while specific symptoms may be improved with treatment.
ME/CFS shares several similarities with long COVID, the collection of symptoms experienced by some people following infection with COVID-19. Many people with long COVID meet diagnostic criteria for ME/CFS, so there is considerable interest in understanding the relationship between the two conditions.
