Chronic fatigue syndrome — also known as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) — is a serious, chronic illness that can cause pain and extreme fatigue.

The Centers for Disease Control and Prevention (CDC) estimate that between 836,000 and 2.5 million people in the United States have ME/CFS, most of whom do not have a diagnosis.

In the past, some people did not believe that ME/CFS was a real illness. However, experts have started to take it more seriously in recent years, and research is underway to find out why it happens and how to treat it.

Meanwhile, lifestyle strategies and medical treatment may help people manage some of the symptoms.

ME/CFS is a complex condition that can affect a range of bodily systems and functions. As a result, the symptoms can vary widely.

Many of the possible symptoms resemble those of other conditions, making ME/CFS hard to diagnose.

Core symptoms

The symptoms of ME/CFS can vary among individuals, but there are three core symptoms:

Reduced ability to do activities that were previously possible

A person with ME/CFS will experience fatigue that interferes with their ability to carry out daily tasks.

The fatigue:

  • is severe
  • does not improve with rest
  • is not due to activity
  • was not previously present

For a diagnosis of ME/CFS, this fatigue and the resulting decrease in activity levels must last 6 months or longer.

Post-exertional malaise

A person with post-exertional malaise (PEM) will experience a “crash” after physical or mental exertion.

During times of PEM, they may have new or worsening symptoms that include:

Following an event that triggers PEM, the person may be unable to leave the house, get out of bed, or do regular chores for several days or even weeks. The symptoms tend to become worse 12–48 hours after the exertion.

The trigger will depend on the individual. For some people, even having a shower or going to the grocery store can trigger PEM.

Sleep disorders

A range of sleep disorders can occur. The person may feel very sleepy but be unable to sleep or not feel refreshed after sleeping. They may experience:

  • intense and vivid dreaming
  • restless legs
  • nighttime muscle spasms
  • sleep apnea

Other key symptoms

As well as the three core symptoms above, one of the following two symptoms must be present for a diagnosis of ME/CFS, according to the CDC.

Problems with thinking and memory

The person may find the following challenging:

  • making decisions
  • focusing on details
  • thinking quickly
  • remembering things

People sometimes refer to these symptoms as “brain fog.”

Dizziness when standing up

When the person moves from lying on their back to sitting or standing, they may experience:

  • dizziness
  • lightheadedness
  • faintness
  • vision changes, such as blurred vision or seeing spots

Other possible symptoms

Pain is a common symptom. A person with ME/CFS will often experience pain or discomfort that does not stem from an injury or other identifiable cause.

Common types of pain include:

  • muscle aches and pains
  • joint pain without redness or swelling
  • headaches

The person may also experience:

In addition, the American Myalgic Encephalomyelitis and Chronic Fatigue Syndrome Society (AMMES) note that other possible symptoms include:

Experts do not know what causes ME/CFS, but some people who have the condition say that it started after another health issue, such as:

  • a flu-like illness
  • a stomach bug or other infection
  • the Epstein-Barr virus, which causes mononucleosis, commonly known as “mono”
  • extreme physical stress, for example, surgery

There is growing evidence of a link between ME/CFS and the way the immune system works, but more research is necessary to establish the mechanism behind this.

According to the Office on Women’s Health, females are two to four times more likely than males to experience ME/CFS. The condition can also affect children, although this is less common.

The symptoms of ME/CFS vary widely and can resemble those of other conditions, which can make it difficult to diagnose.

If a person seeks medical help for ME/CFS, a doctor will likely begin the diagnostic process by:

  • asking about the person’s symptoms
  • carrying out a physical examination
  • recommending tests to try to identify the cause of any symptoms

To receive a diagnosis of ME/CFS, a person must have the three core symptoms of the condition for 6 months or longer. In addition, the doctor must be unable to find another explanation for the symptoms.

It can take time to eliminate other possible causes of ME/CFS symptoms, but there is no specific test that can identify the condition.

In 2018, researchers found that the levels of some molecules appeared to change when people had ME/CFS. One day, this may help make it easier to diagnose ME/CFS, but more studies are necessary before this can happen.

In 2019, another research team announced that they had made further progress in developing a test. The test focused on certain features of blood cells and electrical activity in people with ME/CFS.

In the past, many doctors did not believe that ME/CFS was a real disease, but major health organizations have now begun to recognize it.

Various advocacy groups, including Solve M.E., are working to promote awareness of ME/CFS and empower people with the condition to persist in getting a diagnosis. The AMMES list other advocacy groups on their website, as well as providing useful resources and explaining where people can get support.

There is currently no cure or treatment specific to ME/CFS, but a doctor may work with individuals to help them manage the symptoms. The treatment plan will vary among individuals, as ME/CFS affects people differently.

However, it may involve:

  • focusing on whichever symptom poses the greatest challenge
  • alleviating pain
  • learning new ways to manage activities

Managing PEM

One way to manage fatigue after activity is through pacing, or activity management.

The person will work with a doctor to determine the best way to balance rest and activity. The doctor will also help them identify their personal triggers and establish how much exertion they can tolerate.


ME/CFS causes fatigue, and it can also disrupt sleep. A doctor will encourage the person to establish healthful sleeping habits, such as having a regular sleep schedule.

If these strategies do not help, the doctor may prescribe medication.


At first, a doctor may recommend over-the-counter (OTC) drugs for headaches and other types of pain. If these do not work, they may prescribe stronger medication.

A person with ME/CFS may be sensitive to various chemicals. Therefore, they should speak to a doctor before using any new medication.

Nondrug therapies that may help include:

  • gentle stretching and toning exercises
  • gentle massage
  • heat therapy
  • water therapy

Anxiety and depression

Anxiety and depression are common among people with ME/CFS. Antidepressant drugs may help some people, but they can sometimes make symptoms worse.

Lifestyle remedies that may help include:

Experimental medicines

Some laboratory research has suggested that rituximab (Rituxan), a cancer drug that targets the immune system, could be effective for people with ME/CFS.

However, more research is necessary to ensure that the drug is safe to use in the treatment of this condition.

Various strategies can help people manage ME/CFS.

These include:

  • finding a doctor who understands the condition
  • seeking a counselor who can help manage the emotional and practical challenges
  • making family and friends aware of the symptoms and challenges
  • scheduling rest and activity times to maximize quality of life
  • using calendars and journals to help with memory lapses
  • learning which relaxation techniques are effective for them
  • following a balanced and nutritious diet
  • taking nutritional supplements, if tests reveal a deficiency
  • finding someone to help with child care and household chores at difficult times, if possible

What about exercise?

Gentle stretching, yoga, and tai chi might be helpful in some cases, and at the right time, but vigorous exercise can make symptoms worse.

The CDC note that exercise plans that benefit many people with chronic diseases are not usually suitable for people with ME/CFS, and they may be dangerous.

People with symptoms or a diagnosis of ME/CFS should not follow any type of activity plan without discussing it with their doctor first.

ME/CFS is a life changing condition that can affect every aspect of a person’s daily life.

It can take time to get a diagnosis, as the symptoms are not specific but overlap with those of other conditions. Whether or not a person has a diagnosis, some lifestyle strategies can help them manage the challenges.

Until scientists find a specific treatment, coping strategies will play a key role in managing ME/CFS.