Making sense of ME/CFS, together

Myalgic encephalomyelitis, or ME/CFS, is a long-term illness that causes severe fatigue that does not improve with rest, along with a worsening of symptoms after effort, unrefreshing sleep, brain fog and other symptoms. It is also called chronic fatigue syndrome.

The terms are often used for the same illness, which is why it is written ME/CFS. Myalgic encephalomyelitis is the older name used in some countries, and chronic fatigue syndrome is used in others. Some people prefer ME because fatigue alone does not describe how disabling the illness can be.

The main symptoms are severe fatigue, post-exertional malaise, unrefreshing sleep and problems with thinking and memory. Many people also have pain, dizziness when standing, sore throat or tender glands, and sensitivity to light or sound. Symptoms vary and can change from day to day.

Post-exertional malaise (PEM), sometimes called a crash, is a marked worsening of symptoms after physical, mental or emotional effort. It is a key feature of ME/CFS and different from ordinary tiredness after a busy day.

It is often delayed by a day or two and can last days, weeks or longer. What triggers it varies, and the effort can be small, such as a shower, a conversation or time on a screen.

The exact cause is not known. For many people it starts after an infection such as glandular fever, and it can also follow other physical or emotional stress. Researchers are looking at the immune system, how cells produce energy, the nervous system and genes. It is not contagious and is not caused by laziness or something you did.

There is no single test, so a doctor diagnoses ME/CFS by listening to your symptoms and ruling out other causes. This usually takes a few months of symptoms.

• A conversation about your symptoms, how they started and how effort affects you
• A physical examination, including checking your blood pressure and heart rate lying and standing
• Blood and urine tests to rule out other conditions
• A review of sleep, mood and any medicines you take
• Referral to a specialist service if available

A normal test result does not mean your symptoms are not real, so ask what the next step is if you continue to feel unwell.

ME/CFS is not usually fatal, and most people with it have a normal life expectancy. It can be very disabling and can affect work, relationships and mental health, so support matters. Seek help if you have thoughts of harming yourself.

There is no cure, and recovery differs from person to person. Some people improve over time, especially with good pacing and support, and a smaller number recover fully. Others live with symptoms long term, and symptoms can fluctuate, with good periods and setbacks.

ME/CFS is not classed as an autoimmune disease, but research suggests the immune system may play a part, and scientists are still studying how. It is recognised as a serious physical illness.

Pacing means staying within your energy limits by balancing activity and rest, so you avoid crashes. Many people with ME/CFS find it the most useful strategy, although it does not cure the illness.

• Break tasks into small steps and rest before you feel exhausted
• Alternate physical, mental and social activity
• Stop before symptoms get worse rather than pushing on
• Keep a diary to find your limits and triggers

Not in the usual way. Exercise that steadily increases regardless of how you feel can trigger post-exertional malaise and make symptoms worse. Gentle, carefully paced movement within your limits may suit some people, so agree a plan with a clinician who understands ME/CFS.

It can be. Rules differ by country, but in many places a long-term condition that has a substantial effect on day-to-day activities, such as working, can count as a disability.

This means you may be able to ask for reasonable adjustments at work or school, such as flexible hours or rest breaks. An employer, a disability advice service or a benefits adviser can tell you what applies where you live.

Brain fog describes slowed thinking, trouble concentrating, forgetfulness and difficulty finding words. It is common in ME/CFS and often gets worse when you are tired or after a crash. Pacing, rest, and reducing noise and distractions can help.

They are not the same, but they can look alike. Some people with long COVID have symptoms that meet the criteria for ME/CFS, including post-exertional malaise. If your symptoms began after an infection, tell your doctor so they can consider the right diagnosis.