CFS or Chronic Fatigue Syndrome is a sickness characterized by continuous medically unexplained fatigue. Chronic Fatigue Syndrome may also be called myalgic encephalomyelitis (ME), Epstein-Barr disease, CFIDS or chronic fatigue and immune dysfunction syndrome and post-viral fatigue syndrome. The most conspicuous sign or symptom of CFS is a feeling of unexplained extreme tiredness that is not eased or alleviated by rest. Arthritis and fibromyalgia are mostly frequent accompaniments to patients and people suffering from CFS. Some other symptoms of this illness may also consist of confusion, muscle weakness, unexplained headaches, joint and muscle pains, poor concentration, bowel problems, poor temperature control, difficulty sleeping and forgetfulness.

The condition of chronic fatigue syndrome has always been perceived or viewed as "yuppie flu" or hypochondriacal behavior. Yet now, most experts agree that CFS is a separate illness with physical symptoms. The cause of chronic fatigue syndrome is not well known or understood. This disease is very difficult to diagnose, and several people go on and get by for years without even knowing that they have it. The diagnosis is administered only if no other cause, which includes the side effects of certain drugs, is found to explain the presence of extreme tiredness. Thus, no laboratory tests are accessible to confirm a diagnosis of this disease.

Regardless of whatever the cause is, this illness has a major effect on a person’s quality of life. The unexplained cases of chronic fatigue could be considered or classified as CFS if the person has a minimum of at least half of the following signs and symptoms: sore throat, muscle pain, headaches of a new pattern or type of severity, impairment of short-term concentration and memory, multi-joint pain, tender lymph nodes, extreme tiredness lasting more than a day after physical exertion, and unrefreshing sleep. For a person to be diagnosed officially with CFS, the symptoms should be present and recurring for at least six months.

However, if the symptoms experienced do not meet the criteria for chronic fatigue syndrome, then the condition is pertained to as idiopathic chronic fatigue. There are some theories which suggests that chronic tiredness is linked to physical inactivity, overwork, low blood pressure, stress, hypoglycemia, colitis, hormonal imbalance, problems with the immune system and brucellosis could also cause CFS. Certain conditions such as toxins and virus infection have been proposed to further trigger to the development of this disease. CFS is indeed a frustrating disease that affects people of all ages. Females are diagnosed with this illness two to four times as often as males are.

However, it is not clear whether chronic fatigue syndrome affects females more frequently—or if women report their condition to their physicians more often than men do. Because there is no definite diagnostic test for this disease, no one knows precisely how many people suffer or afflicted from CFS. Nevertheless, it is estimated that half a million Americans suffer from chronic fatigue syndrome. Treating this illness poses a clear and important challenge to patients suffering from this and also to their healthcare and medical practitioners.