Chronic fatigue syndrome

What is chronic fatigue syndrome?

Myalgic encephalomyelitis, also called chronic fatigue syndrome or ME/CFS, is a long-term condition that affects many parts of the body, most commonly the nervous and immune systems. Its main feature is extreme, persistent tiredness that doesn't improve with rest, alongside other symptoms that get worse after physical or mental effort.

Symptoms of chronic fatigue syndrome

ME/CFS causes a specific pattern of symptoms. The main ones are:

• overwhelming fatigue that doesn't go away with rest or sleep, and makes everyday tasks like showering, working or studying difficult
• post-exertional malaise (PEM): your symptoms get noticeably worse after physical or mental activity, sometimes hours or days later, and it can take days, weeks, or even longer to recover
• sleep problems, including trouble falling or staying asleep, sleeping too much, or waking up feeling unrefreshed and stiff
• problems with thinking, concentration and memory, often described as 'brain fog'.

Many people also have orthostatic intolerance, feeling dizzy, lightheaded or faint when standing or sitting upright, along with:

• muscle or joint pain, and headaches
• a sore throat or tender glands in the neck or armpits
• digestive problems, such as bloating or symptoms similar to irritable bowel syndrome
• sensitivity to light, sound, smells, foods or chemicals
• flu-like symptoms, such as chills or night sweats
• changes in blood pressure, palpitations, or feeling short of breath on standing or with exertion.

Symptoms can vary a lot from person to person, and can change from day to day or even hour to hour. ME/CFS is generally described using four levels of severity: mild (around a 50% reduction in your pre-illness activity levels), moderate (mostly housebound), severe (mostly bedridden), and very severe (bedridden and needing help with basic care such as eating and drinking).

Causes and who is at risk

The exact cause of ME/CFS isn't known, and there may be more than one. Researchers are looking into several possible triggers and contributing factors, including:

• infections, such as glandular fever (Epstein-Barr virus) or, more recently, COVID-19, some people who develop long COVID have symptoms very similar to ME/CFS
• changes in the immune system
• physical or emotional stress
• changes in how your cells produce energy
• genetics; ME/CFS can sometimes run in families.

For some people, symptoms start suddenly, following an infection, an operation, or another physical or emotional trauma. For others, it develops gradually over months or years, without an obvious trigger.

ME/CFS can affect anyone, including children, but it's most commonly diagnosed in people aged 40 to 60, and adult women are affected more often than men, in some estimates as much as three to four times more. It is not caused by being unfit, or by a mental health problem.

Are there different types of chronic fatigue syndrome?

ME/CFS isn't divided into separate named types in the way some conditions are. Instead, it's usually described by how it starts and how severe it is. It can begin suddenly, often after an infection or a stressful physical event, or it can develop gradually over months or years.

Severity is generally described in four levels:

• mild: around a 50% reduction in the activity levels you had before becoming ill
• moderate: you're mostly housebound
• severe: you're mostly bedridden
• very severe: you're bedridden all the time, and need help with basic care such as eating and drinking.

Severity can change over time. Some people improve gradually, some stay stable, and others find their symptoms get worse.

How is chronic fatigue syndrome diagnosed?

There's no blood test, scan or other single test that can diagnose ME/CFS. Instead, your doctor will diagnose it based on your symptoms, after ruling out other conditions that could be causing them. This usually involves:

• asking about your symptoms and medical history, including your family's history
• a physical and mental health examination
• blood and urine tests, to check for other illnesses that could explain your symptoms.

To be diagnosed, you'll generally need to have had persistent, unexplained fatigue for at least 6 months that isn't caused by ongoing over-exertion and isn't much relieved by rest, along with post-exertional malaise and unrefreshing sleep. You'll also usually need at least one of: problems with thinking or memory, or orthostatic intolerance.

Because there's no specific test and symptoms overlap with several other conditions, it can take a long time to get a firm diagnosis. If you're not recovering as quickly as expected from what seems like a common illness, it's worth raising ME/CFS with your doctor.

How is chronic fatigue syndrome treated?

There's no cure for ME/CFS, but several approaches can help you manage symptoms. The right combination is individual, so it's worth working with your doctor to decide what to prioritise first, often whichever symptom is causing you the most difficulty.

Energy management, or pacing, is a central strategy. This means learning to balance activity with rest so you stay within your available energy, rather than doing too much on a good day and then 'crashing' afterwards. Because PEM can be delayed by 24 to 48 hours, tools like an activity diary, pedometer or heart rate monitor can help you notice patterns and identify your own limits before you overdo it.

Other options include:

• medicines to help with specific symptoms, such as pain, sleep problems, or headaches
• counselling, to help you cope with the impact of the illness on your life
• nutritional support or supplements, if your doctor recommends them
• complementary therapies such as gentle massage or relaxation techniques.

If you do feel able to exercise, this should be gentle and carefully paced, for example short walks, stretching or seated tai chi, stopping well before symptoms flare, and should never be pushed through if your body is telling you to stop.

Be cautious of any treatment promoted as a cure for ME/CFS. Some are unproven, costly, and could even be harmful, so always check with your doctor before trying something new.

When should I see a doctor?

See your GP if you have persistent, overwhelming fatigue that doesn't improve with rest, especially if it's lasting longer than you'd expect from a common illness, or if it's affecting your ability to work, study or manage daily life.

Living with ME/CFS can also affect your mental and emotional wellbeing, and some people experience low mood or a higher risk of suicidal thoughts, often linked to the impact the illness has on their work, activities and sense of self. If you're finding things difficult, talk to your doctor. If you ever feel unsafe or have thoughts of suicide, contact a crisis service or your local emergency services straight away.