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Medical Description

Doctors and scientists are not sure what causes chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), but the illness often develops following a cold or flu. Genetic studies have been done that show that it is a physical illness, and that people who have close family members who have CFS/ME are at greater risk for developing the illness.

Signs and Symptoms

The signs and symptoms of CFS/ME include some or all of the following:

The main symptom of CFS/ME is fatigue. The fatigue of CFS/ME is different from the fatigue that non-affected people experience. Usually when we overexert ourselves, we feel "tired" for a short period and feel refreshed after a period of relaxation or sleep. With CFS/ME, the fatigue is severe. The "malaise" felt by individuals with CFS/ME following exercise, or even routine activities, has been compared to the pain, fatigue and discomfort associated with a severe flu. This post-exertional malaise usually lasts for 24 hours or more. It is often accompanied by decreased mental functioning. For example, a person with CFS/ME may have to rest in bed for three hours to recover after shopping for half an hour or making a bowl of soup.

The fatigue is often severe enough to significantly reduce a person’s ability to perform regular activities. It decreases a person’s activity level to at least 50 percent. This affects all aspects of a patient's life – his or her social life, work life, time with family and friends.

Sleep Dysfunction
People with CFS/ME often experience various types of sleep disturbance, such as insomnia, difficulty getting to sleep, waking up frequently and a reduced amount of deep sleep. After sleeping, they may wake up feeling as tired as they did before going to bed.

Pain is felt throughout the body. The pain can be a sharp, shooting, burning or aching pain in the muscles. Approximately 75 percent of people with CFS/ME experience pain in the tender points associated with fibromyalgia; however, the pain is not limited to these tender points. Joints are often sore, but not swollen. Many people also develop new headaches with the illness, including tension headaches, pressure headaches and migraines. Pain can interfere with a person’s sleep.

Brain Function Problems
Perhaps the most disturbing aspect of CFS/ME is the loss of cognitive function that people experience, particularly when they have overextended themselves. People with CFS/ME often experience "brain fog" or confusion. They may have difficulty concentrating, process information more slowly, grope for words and have difficulty multi-tasking. They may have short-term memory problems, to the point where they forget about plans they made, where they parked the car, or what they just read in a book.

Other common brain function symptoms include loss of depth perception, blurred vision, loss of balance and increased sensitivity to "sensory stimuli," such as light, sound and odours. People with CFS/ME are more easily "overloaded" by sensory stimuli, too much information, emotional stress or physical effort. They may not be able to block out background noise to listen to conversations, while at a party, for example. This "overload” phenomenon may lead to a "crash," where the person becomes immobilized by physical and mental fatigue. The cognitive symptoms become worse as the person becomes more fatigued and anxious.

Problems with Automatic Body Functioning (Autonomic Nervous System)
The autonomic nervous system regulates key functions in our bodies that occur "automatically," without us thinking about them. This includes, for example, keeping our heart beating, our blood pressure regulated, our stomach and intestines functioning properly and our lungs working. A variety of symptoms result when this system is affected by CFS/ME.

Many people with CFS experience a drop in blood pressure either when standing up or after standing for about 10 minutes. This can cause light-headedness, dizziness, heart palpitations, shortness of breath and sweating.

Other common symptoms may include diarrhea, constipation, nausea, gas and bloating.

Hormonal and Endocrine Symptoms
People with CFS/ME may have trouble maintaining a steady body temperature, and feel cold all the time or feel hot and feverish.

Other symptoms may include weight loss or noticeable weight gain. Some people with CFS/ME "crash" – experience a period of immobilizing physical and/or mental fatigue. This often happens when a person is "overloaded" physically, mentally or emotionally.

Virus-Like Symptoms
Some people with CFS have virus-like symptoms. They feel "unwell" and feverish, have a sore throat and swollen lymph glands. These symptoms usually occur at the onset of the illness but may also occur later on and be triggered by a “crash” or overdoing activities.

Chemical Sensitivities/Intolerances
Other common symptoms include chemical sensitivities/intolerances, for example, to perfumes, cigarette smoke, diesel fuel, certain foods or medications.

The symptoms of CFS/ME tend to ebb and flow. Symptoms worsen with physical or mental exertion and increased stress, and usually improve as individuals learn to pace themselves and cope with their illness. Also, symptoms tend to be worse at the beginning of the illness.

Some people with mild CFS/ME recover within one to two years, and do not have a relapse if they learn to respect the physical limitations of their bodies. Others with severe CFS/ME live with CFS for several years or, in some cases, for the rest of their lives. CFS/ME can be mild, moderate or severely disabling.


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Chronic Fatigue Syndrome

Medical description


Living with CFS/ME

Activity and exercise




Pain relief


Coping emotionally

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