Myalgic encephalomyelitis/chronic fatigue syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disabling chronic illness. People with ME/CFS experience profound fatigue that does not go away with rest, as well as sleep issues and problems with memory or concentration. The hallmark symptom is post-exertional malaise (PEM), a worsening of the illness that can start immediately or hours to days after even minor physical or mental activity. This "crash" can last from hours or days to several months. Further common symptoms include dizziness or faintness when upright and pain.^[3][10]

The cause of the disease is unknown.^[11] ME/CFS often starts after an infection, such as mononucleosis.^[12] It can run in families, but no genes that contribute to ME/CFS have been confirmed.^[13] ME/CFS is associated with changes in the nervous and immune systems, as well as in energy production.^[14] Diagnosis is based on distinctive symptoms, and a differential diagnosis, because no diagnostic test such as a blood test or imaging is available.^{[7][15][16][17]}

Symptoms of ME/CFS can sometimes be treated and the illness can improve or worsen over time, but a full recovery is uncommon.^[12][18] No therapies or medications are approved to treat the condition, and management is aimed at relieving symptoms.^[2]: 29 Pacing of activities can help avoid worsening symptoms, and counselling may help in coping with the illness.^[8] Before the COVID-19 pandemic, ME/CFS affected two to nine out of every 1,000 people, depending on the definition.^[9] However, many people fit ME/CFS diagnostic criteria after developing long COVID.^[19] ME/CFS occurs more often in women than in men. It is more common in middle age, but can occur at all ages, including childhood.^[20]

ME/CFS has a large social and economic impact, and the disease can be socially isolating.^[21] About a quarter of those affected are unable to leave their bed or home.^[10]: 3 People with ME/CFS often face stigma in healthcare settings, and care is complicated by controversies around the cause and treatments of the illness.^[22] Doctors may be unfamiliar with ME/CFS, as it is often not fully covered in medical school.^[19] Historically, research funding for ME/CFS has been far below that of diseases with comparable impact.^[23]