ME/CFS FAQs: common questions answered

There is no blood test or scan that can confirm ME/CFS. Diagnosis is clinical, meaning a doctor makes it based on your symptoms, your history, and by ruling out other conditions that could explain how you feel.

In the UK, the NICE NG206 guideline sets out the process. A doctor can suspect ME/CFS once the core symptoms, including PEM, have been present for six weeks in adults, or four weeks in children and young people. The diagnosis itself can be confirmed after three months of persistent symptoms, provided other causes have been excluded.

That exclusion step usually means blood and urine tests to check for things like anaemia, thyroid problems, and diabetes, which can cause similar fatigue. This is a normal and important part of the process, not a sign your doctor doubts you.

The three-month point matters. You may see six months quoted elsewhere. That figure comes from the 2015 US criteria, which are still in use internationally. England and Wales have used the three-month threshold since 2021, and the shorter timeframe is intended to get people diagnosed and supported sooner.

For the full process, see how ME/CFS is diagnosed.

There is no cure for ME/CFS yet. Individual symptoms, such as sleep disruption, pain, and dizziness, can often be treated with medication or lifestyle adjustments. The central management strategy is pacing, which helps prevent crashes and protect your baseline over time.

Some people do recover, and many improve to some degree. Others remain ill for life. Trajectories vary widely and cannot be predicted at diagnosis.

ME/CFS and fibromyalgia share several features, and some people meet the diagnostic criteria for both.

The distinguishing difference is what sits at the centre of the illness. In ME/CFS, the defining feature is PEM, a delayed, disproportionate worsening of symptoms after physical or mental effort.

In fibromyalgia, the defining feature is widespread pain.

Fatigue is significant in both, but it behaves differently. Fibromyalgia flares can be triggered by many things, but they do not follow the specific pattern that defines PEM.

Long Covid is an umbrella term for symptoms that persist after a Covid-19 infection. ME/CFS is a specific illness defined by PEM and other core symptoms, which can be triggered by a wide range of infections, not only Covid-19.

A significant proportion of people with Long Covid meet the diagnostic criteria for ME/CFS. Where that is the case, ME/CFS management approaches, particularly pacing and PEM avoidance, generally apply. But not everyone with Long Covid has ME/CFS, and not everyone with ME/CFS had Covid-19.

ME/CFS is frequently misdiagnosed as depression or burnout because all three involve profound exhaustion.

The key difference is motivation and physical response to activity. People with depression often lose interest in things they used to enjoy. People with ME/CFS typically retain that interest. Their bodies cannot follow through. Exercise tends to improve depression symptoms. In ME/CFS, exertion can cause a significant and prolonged worsening of symptoms.

No. ME/CFS itself is not contagious.

The illness is often triggered by a contagious virus, such as Epstein-Barr (glandular fever), influenza, or Covid-19. The virus itself can be passed on, but the ME/CFS that sometimes develops afterwards is the body’s own response to that infection. That response cannot be transmitted to someone else.

People with ME/CFS cannot give blood in the UK, however, and that exclusion is permanent, applying even to people who have recovered. NHS Blood and Transplant gives two reasons: the strain of donating can harm the donor, and it is not yet known whether any disease process involved could affect the blood itself. Long Covid and post-viral fatigue syndromes have since been added to the same list.

Research suggests genetics may play a role. ME/CFS can run in families, and having a close relative with the condition is associated with a higher risk of developing it.

The UK DecodeME study is the largest investigation into the genetic basis of the condition to date, drawing on DNA from more than 21,000 people with ME/CFS. In 2025 it identified eight regions of the genome that differ in people with ME/CFS, pointing to both the immune system and the nervous system as part of the underlying biology. Notably, the study found no shared genetic basis between ME/CFS and depression or anxiety, further evidence that this is a distinct physical illness.

These findings were released as a preprint in August 2025 and have not yet completed peer review. Further work is underway. They are, even so, the strongest biological evidence to date that ME/CFS has genetic roots.

Genetics appears to be one of several factors, alongside infection, physical trauma, and prolonged stress, that can contribute to the condition developing.

The honest answer is that the cause is not yet fully understood. What is clear is that ME/CFS is not caused by laziness, deconditioning, or a psychological problem.

Several factors appear to contribute. The illness is very often triggered by an infection, such as Epstein-Barr (glandular fever), influenza, or Covid-19. Genetics seem to play a part, as do physical trauma and prolonged periods of stress. For many people, it begins after an infection they never fully recover from.

Current research points to the immune system, the nervous system, and the way the body produces and uses energy. The 2025 DecodeME findings add weight to the immune and neurological picture. The mechanism that keeps people ill, rather than what first triggers it, is still being worked out, and is the focus of much ongoing research.

For more, see causes and triggers.

Yes. ME/CFS is more commonly diagnosed in women, around two to three times as often, but men can and do develop the condition. The data NICE cites puts the figure at about 2.4 times.

Some researchers think ME/CFS is underdiagnosed in men, partly because diagnostic patterns and clinical research have historically been shaped around female presentation.

Yes. ME/CFS affects children and teenagers as well as adults, and it is a recognised cause of long-term school absence.

Research suggests two peak ages for the illness developing: adolescence, roughly 10 to 19, and the mid-thirties.

The diagnostic timings differ slightly for children. NICE allows ME/CFS to be suspected after four weeks of symptoms rather than the six weeks used for adults, though the diagnosis is still confirmed at three months for everyone. NICE also recommends referral to a paediatrician rather than an adult specialist team.

The core features are the same, but the impact can look different. Lost schooling, disrupted friendships, and the difficulty of being believed all weigh heavily on a young person, and families often have to advocate hard for appropriate support.

There is no single answer. Effective management combines several strategies: pacing to stay within your energy envelope, radical rest to support recovery, treatment of individual symptoms such as pain and unrefreshing sleep, and emotional support for the adjustment of living with a long-term illness.

For more, see our living with ME/CFS section, managing ME/CFS section or our pacing guide.