Obviously, as is implied by the various names, fatigue is the major symptom in CFS. People often have the misconception that this is the only symptom and hence they assume that sufferers simply like to complain about the normal tiredness that everyone experiences after a day at work etc. CFS is actually much more than fatigue, and the fatigue experienced is a lot more severe than simple tiredness. The following is a list of the major symptoms of CFS.

• Fatigue - This can be both physical and mental fatigue. It is a pronounced fatigue that leads to a significant reduction in ability to carry out normal tasks and live your usual lifestyle. The fatigue is usually ever present to some degree and is not relieved by sleep; in fact it may be a lot worse upon waking, especially after a lot of activity the previous day.

• Exercise Intolerance - A major feature shared by CFS sufferers is the lack of exercise tolerance. Although they may feel reasonably good before exercise, shortly after commencing they feel absolutely exhausted and cannot continue. It is the same thing a marathon runner experiences and is commonly known as "hitting the wall". This phenomenon occurs because the body’s cells requirement for oxygen exceeds the supply so they switch to anaerobic (without oxygen) respiration and lactic acid builds up in the muscles.

• Severe Malaise - A general feeling of being ill. It can be described as a "flu-like" or "hangover" feeling.

• Muscle and Joint Aches - These can occur anywhere in the body but the most common sites are the lower back and legs. The aching can be severe and is aggravated substantially by any exertion, physical or mental. There is significant overlap here with Fibromyalgia and many patients are diagnosed with both CFS and Fibromyalgia.

• Cognitive Dysfunction - Symptoms of cognitive dysfunction are a prominent problem in CFS. They include poor concentration, memory loss (constantly forgetting simple information like names and numbers), inability to take in information (having to read the same thing over and over) and a general reduction in cognitive ability and IQ.

• Chronic Headache - As would be expected in someone who feels "ill all over" and achy in general, headaches are a common complaint in CFS. They are different to headaches experienced before the onset of CFS and their severity usually varies inline with other aches and symptoms.

• Balance Disturbance - An unusual but common symptom is a loss of balance or sensation of dizziness. This most often occurs upon standing up and the sufferer may feel faint and even black out. This is often referred to as 'Neurally Mediated Hypotension (NMH)' or ‘Orthostatic Intolerance’ and is most likely due to low blood pressure or abnormal blood flow to the brain.

• Recurrent Sore Throat - A persistent sore throat and/or swollen glands commonly precedes the onset of CFS and may continue as the illness progresses. This is felt to be an indicator that a viral infection plays a major role in cause of the illness.

• Mood and Sleep Disturbances - Depression, anxiety and irritability are often present which frequently leads to misdiagnosis by doctors. Sleep disturbances are common and may present as hypersomnolence (sleeping more than normal), sleep reversal i.e. sleeping all day and awake at night, or insomnia (inability to sleep). Sleep apnea and Restless Leg Syndrome (RLS) are also common..

• Abdominal Pain andDigestive Disturbances - These are symptoms similar to Irritable Bowel Syndrome and, as with Fibromyalgia, CFS sufferers are often diagnosed with IBS.

• Nausea - Particularly apparent when other symptoms feeling particularly ill in general.

• Heightened Sensitivity to Light and/or Sound - Normal everyday levels of sound and light can seem overwhelming to a CFS sufferer. A busy place like a large shop will leave a sufferer totally exhausted very rapidly.

• Visual Disturbances - These may include a blurring of vision, especially when reading, and eye pain.

• Skin Sensitivity - This is another unusual symptom. Some CFS sufferers experience a sensation where patches of skin become very sensitive to touch and may feel like they are burning. Some people describe this as a "crawling sensation".

The number and severity of symptoms varies drastically between individuals but the symptoms of fatigue, malaise, cognitive dysfunction and possibly muscle aches, are the core symptoms of the illness.

An important thing to note is that all symptoms are generally made a lot worse by physical or mental exertion of any kind. It is common for the severity of the illness to wax and wane from day to day as well as over longer periods of weeks and months. Patients frequently experience periods of remission and relapse.

Additional signs and symptoms

In addition, people with chronic fatigue syndrome have reported other various signs and symptoms that aren't part of the official definition of chronic fatigue syndrome determined by the International Chronic Fatigue Syndrome Study Group. These include:

• Alcohol intolerance
• Bloating
• Chest pain
• Chronic cough
• Diarrhea
• Dizziness
• Dry eyes and mouth
• Earache
• Irregular heartbeat
• Jaw pain
• Morning stiffness
• Night sweats
• Psychological problems, such as depression, irritability, anxiety disorders and panic attacks
• Shortness of breath
• Tingling sensations
• Weight loss

If you have chronic fatigue syndrome, your symptoms may peak and become stable early on, and then come and go over time. Some people go on to recover completely, while others grow progressively worse.