Although its name trivializes the illness as little more than mere tiredness, it brings with it a huge aray of debilitating symptoms.

CFIDS is characterized by incapacitating fatigue (experienced as profound exhaustion and extremely poor stamina) and problems with concentration and short-term memory. It is also accompanied by flu-like symptoms such as pain in the joints and muscles, unrefreshing sleep, tender lymph nodes, sore throat and headache. A distinctive characteristic of the illness is post-exertional malaise, a worsening of symptoms following physical or mental exertion occurring within 12-48 hours of the exertion and requiring an extended recovery period.

The symptoms of CFIDS are highly variable and fluctuate in severity, complicating treatment and the ill person’s ability to cope with the illness. Most symptoms are invisible, which makes it difficult for others to understand the vast array of debilitating symptoms with which people with the illness must contend.

Additional symptoms are frequently reported by people with CFIDS (PWCs) such as word-finding difficulties, inability to comprehend/retain what is read, inability to calculate numbers and impairment of speech and/or reasoning. PWCs may also have visual disturbances (blurring, sensitivity to light, eye pain, need for frequent prescription changes); psychological problems (depression, irritability, anxiety, panic attacks, personality changes, mood swings); chills and night sweats; shortness of breath; dizziness and balance problems; sensitivity to heat and/or cold; alcohol intolerance; irregular heartbeat; irritable bowel (abdominal pain, diarrhea, constipation, intestinal gas); low-grade fever or low body temperature; numbness, tingling and/or burning sensations in the face or extremities; dryness of the mouth and eyes (sicca syndrome); gynecological problems including PMS and endometriosis; chest pains; rashes; ringing in the ears (tinnitus); allergies and sensitivities to noise/sound, odors, chemicals and medications; weight changes without changes in diet; light-headedness; mental fogginess; fainting; muscle twitching; and seizures.