At the present time, there is no blood or other laboratory test to diagnose ME/CFS. The diagnosis is based on the symptoms described by patients, after other possible causes for the symptoms are ruled out. The symptoms must have been present for at least 6 months in adults and 3 months in children.
The effects of these symptoms can vary from person to person. The overall symptoms can be mild to severely disabling. The symptoms can also be more, or less, severe in the same person from one day to the next. Symptoms seem to become more severe with physical or mental exertion (effort) and increased stress.
The most common symptom of ME/CFS is disabling fatigue and malaise (feeling unwell, flu-like symptoms) that becomes much worse after even a small amount of physical effort or exertion, and lasts for 24 hours or more (PEM). The fatigue can be severe enough to interrupt a person’s normal daily routine and interfere with his/her relationships with others, family life, and ability to work.
Sleep dysfunction can include being unable to go to sleep (insomnia), disturbed sleep (waking up many times during the night) and/or a lack of deep, energy-restoring sleep (this is called non-restorative sleep). A person with ME/CFS will often say that he/she woke up feeling just as tired as before he/she went to bed.
A person with ME/CFS will often experience pain throughout the body. The pain may be described as “sharp”, “’burning”, “stabbing or shooting” or “aching” in the muscles. Joints are often sore, but not swollen. Headaches, including tension headaches, pressure headaches and migraines can develop as part of the disease. The presence of pain of any kind can also be a cause of sleep disturbances.
“Cognitive function” refers to mental processes that involve our senses (what we see, hear, smell, taste, and feel), our memory, and our thinking, reasoning and judgement. “Brain fog” or confusion can affect people with ME/CFS, most often when they are in a state of extreme fatigue. There may be difficulty with concentration, listening, and processing information. Even simple tasks can be difficult to manage and may take much longer to accomplish than normal. Short-term memory loss can lead to other frustrating problems in daily life, such as losing items, missing appointments, forgetting names of people you know, etc.
Other brain function problems can include:
Having problems with vision, such as blurred vision and problems with depth perception.
Becoming very sensitive to light, sound and odours, all of which stimulate (or “fire up”) the nervous system.
Being unable to deal with or block out extra stimuli can lead to added physical and mental fatigue. When this becomes more severe, the person can be immobilized in what is known as a “crash”.
The autonomic nervous system governs the body functions that happen without us thinking about them. These include controlling heartbeat, blood pressure, breathing, and digestion. When a person’s autonomic nervous system is affected, he or she can experience low blood pressure after getting up from sitting or lying down or after standing for a period of time. This can cause the person to feel light-headed or dizzy, with heart palpitations, shortness of breath and sweating. Disturbed function of the digestive system can cause diarrhea, constipation, nausea, gas and bloating.
- Flu-like symptoms such as mild fever, sore throat, neck tenderness and/or swollen glands. These can occur at the start of ME/CFS, or later on if the person is over-tired and in a “crash” situation.
- If the hormonal or endocrine (gland) systems are affected, problems with regulating body temperature can cause a person to feel hot, or cold all of the time. Noticeable changes in body weight can also occur.
- Chemical sensitivities or intolerance may include substances such as cigarette smoke, perfumes, diesel fuel, some foods, and some medications.