Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complicated disorder.

It causes extreme fatigue that lasts for at least six months. Symptoms worsen with physical or mental activity but don't fully improve with rest.

The cause of ME/CFS is unknown, although there are many theories. Experts believe it might be triggered by a combination of factors.

There's no single test to confirm a diagnosis. You may need a variety of medical tests to rule out other health problems that have similar symptoms. Treatment for the condition focuses on easing symptoms.

Symptoms of ME/CFS can vary from person to person, and the severity of symptoms can fluctuate from day to day. In addition to fatigue, symptoms may include:

• Extreme exhaustion after physical or mental exercise.
• Problems with memory or thinking skills.
• Dizziness that worsens with moving from lying down or sitting to standing.
• Muscle or joint pain.
• Unrefreshing sleep.

Some people with this condition have headaches, sore throats, and tender lymph nodes in the neck or armpits. People with the condition also may become extra sensitive to light, sound, smells, food and medicines.

When to see a doctor

Fatigue can be a symptom of many illnesses. In general, see your doctor if you have persistent or excessive fatigue.

The cause of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is still unknown. A combination of factors may be involved, including:

• Genetics. ME/CFS appears to run in some families, so some people may be born with a higher likelihood of developing the disorder.
• Infections. Some people develop ME/CFS symptoms after getting better from a viral or bacterial infection.
• Physical or emotional trauma. Some people report that they experienced an injury, surgery or significant emotional stress shortly before their symptoms began.
• Problems with energy usage. Some people with ME/CFS have problems converting the body's fuel, primarily fats and sugars, into energy.

Factors that may increase your risk of ME/CFS include:

• Age. ME/CFS can occur at any age, but it most commonly affects young to middle-aged adults.
• Sex. Women are diagnosed with ME/CFS much more often than men, but it may be that women are simply more likely to report their symptoms to a doctor.
• Other medical problems. People who have a history of other complex medical problems, such as fibromyalgia or postural orthostatic tachycardia syndrome, may be more likely to develop ME/CFS.

Symptoms of ME/CFS can come and go, and often are triggered by physical activity or emotional stress. This can make it difficult for people to maintain a regular work schedule or to even take care of themselves at home.

Many people may be too weak to get out of bed at different points during their illness. Some may need to use a wheelchair.

There's no single test to confirm a diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Symptoms can mimic those of many other health problems, including:

• Sleep disorders. Fatigue can be caused by sleep disorders. A sleep study can determine if your rest is being disturbed by disorders such as obstructive sleep apnea, restless legs syndrome or insomnia.
• Other medical problems. Fatigue is a common symptom in several medical conditions, such as anemia, diabetes and underactive thyroid. Lab tests can check your blood for evidence of some of the top suspects.
• Mental health issues. Fatigue is also a symptom of a variety of mental health problems, such as depression and anxiety. A counselor can help determine if one of these problems is causing your fatigue.

It's also common for people who have ME/CFS to also have other health problems at the same time, such as sleep disorders, irritable bowel syndrome or fibromyalgia.

In fact, there are so many overlapping symptoms between this condition and fibromyalgia that some researchers consider the two disorders to be different aspects of the same disease.

Diagnostic criteria

Guidelines proposed by the United States Institute of Medicine define the fatigue associated with ME/CFS as being:

• So severe that it interferes with the ability to engage in pre-illness activities.
• Of new or definite onset.
• Not substantially alleviated by rest.
• Worsened by physical, mental or emotional exertion.

To meet the Institute of Medicine's diagnostic criteria for this condition, a person would also need to experience at least one of these two symptoms:

• Difficulties with memory, focus and concentration.
• Dizziness that worsens with moving from lying down or sitting to standing.

These symptoms must last for at least six months and occur at least half the time at moderate, substantial or severe intensity.

There is no cure for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Treatment focuses on symptom relief. The most disruptive or disabling symptoms should be addressed first.

Medications

Some problems associated with ME/CFS can be improved with certain medicines. Examples include:

• Pain. If medicines such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve) don't help enough, prescription drugs sometimes used to treat fibromyalgia might be options for you. These include pregabalin (Lyrica), duloxetine (Cymbalta), amitriptyline or gabapentin (Neurontin).
• Orthostatic intolerance. Some people with this condition, particularly adolescents, feel faint or nauseated when they stand or sit upright. Medications to regulate blood pressure or heart rhythms may be helpful.
• Depression. Many people with long-term health problems, such as ME/CFS, are also depressed. Treating your depression can make it easier for you to cope with the problems associated with having a chronic disease. Low doses of some antidepressants also can help improve sleep and relieve pain.

Pacing for post-exertional malaise

People with ME/CFS have a worsening of their symptoms after physical, mental or emotional effort. This is called post-exertional malaise. It usually begins within 12 to 24 hours after the activity, and it can last for days or weeks.

People who have post-exertional malaise often struggle to find a good balance between activity and rest. The goal is to remain active without overdoing it. This is also called pacing.

The goal of pacing is to reduce post-exertional malaise, rather than getting back to the same activity level you had when you were healthy. As you improve, you may be able to safely engage in more activity without triggering post-exertional malaise.

It may help to keep a daily diary of your activities and symptoms, so you can track how much activity is too much for you.

Addressing sleep problems

Lack of sleep can make other symptoms more difficult to deal with. Your health care team might suggest avoiding caffeine or changing your bedtime routine. Sleep apnea can be treated by using a machine that delivers air pressure through a mask while you sleep.

Many alternative therapies have been promoted for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), but very few have evidence that they work. Patients with this condition may be sensitive to medications, including herbal products and supplements. Treatments that are expensive or potentially harmful should be avoided.

The experience of ME/CFS varies from person to person. Emotional support and counseling may help you and your loved ones deal with the uncertainties and restrictions of this disorder.

Talking with a counselor can help build coping skills to deal with chronic illness, address limitations at work or school, and improve family dynamics. It also can be helpful if you are dealing with symptoms of depression.

You may find it helpful to join a support group and meet other people with your condition. Support groups aren't for everyone, and you may find that a support group adds to your stress rather than relieves it. Experiment and use your own judgment to determine what's best for you.

If you have signs and symptoms of ME/CFS, you're likely to start by seeing your family's health care professional.

What you can do

Before your appointment, you may want to write a list that includes:

• Your signs and symptoms. Be thorough. While fatigue may be affecting you most, other symptoms — such as memory problems or headaches — also are important to share.
• Key personal information. Recent changes or major stressors in your life can play a very real role in your physical well-being.
• Health information. List any other conditions for which you're being treated and the names of any medications, vitamins or supplements that you take regularly.
• Questions to ask your health care team. Creating your list of questions in advance can help you make the most of your time during your appointment.

For chronic fatigue syndrome, some basic questions to ask your health care team include:

• What are the possible causes of my symptoms or condition?
• What tests do you recommend?
• If these tests don't pinpoint the cause of my symptoms, what additional tests might I need?
• On what basis would you make a diagnosis of ME/CFS?
• Are there any treatments or lifestyle changes that could help my symptoms now?
• Do you have any printed materials I can take with me? What websites do you recommend?
• What activity level should I aim for while we're seeking a diagnosis?
• Do you recommend that I also see a mental health provider?

Don't hesitate to ask other questions during your appointment as they occur to you.

What to expect from your doctor

Your health care team is likely to ask you a number of questions, such as:

• What are your symptoms and when did they begin?
• Does anything make your symptoms better or worse?
• Do you have problems with memory or concentration?
• Are you having trouble sleeping?
• How has this condition affected your mood?
• How much do your symptoms limit your ability to function? For example, have you ever had to miss school or work because of your symptoms?
• What treatments have you tried so far for this condition? How have they worked?