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Symptoms of Chronic Fatigue Syndrome (CFS)

  • Amy Scholten, MPH
Publication Type:

Condition InDepth

Symptoms of Chronic Fatigue Syndrome (CFS)

CFS symptoms can make it hard to do everyday activity. They also differ among people. Symptoms may appear fast or build slowly over time. They may also appear after an infection such as a cold. The infection goes away, but severe tiredness lingers. Symptoms can be constant or may come and go.

The main symptoms for CFS include:

  • Problems doing the same amount of activity as before the illness. This includes work, school, social events, or exercise. It may worsen with time.
  • Physical or mental tiredness that gets worse with activity. Tiredness can last more than 24 hours.
  • Tiredness that does not get better with rest or a full night's sleep.
  • Problems falling or staying asleep, or the need to nap during the day.
  • "Brain fog"—problems with memory, focus, or confusion.
  • Lightheadedness or vision problems when standing or sitting up.

Other symptoms may include:

  • Long-lasting pain that may include:
    • Muscle aches
    • Joint pain (without swelling or redness)
    • Headaches
  • Flu-like symptoms, such as:
    • Frequent sore throat
    • Tender lymph nodes
    • Chills and night sweats
  • Mood swings
  • Mental health problems, such as:
  • Irritable bowel syndrome
  • Allergies
  • Sensitivity to many chemicals, noise, or food

The severity of symptoms varies from person to person. Some people are mildly impaired with CFS. Others may need assistance.


  • Bateman L, Bested AC, et al. Myalgic encephalomyelitis/chronic fatigue syndrome: essentials of diagnosis and management. Mayo Clin Proc. 2021;96(11):2861-2878.
  • Chronic fatigue syndrome. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/chronic-fatigue-syndrome.
  • Chronic fatigue syndrome. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/special-subjects/chronic-fatigue-syndrome/chronic-fatigue-syndrome.
  • Symptoms of ME/CFS. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/me-cfs/symptoms-diagnosis/symptoms.html.


  • Marcin Chwistek, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.