Understanding Chronic Fatigue Syndrome (CFS/ME): Symptoms, Causes, and Diagnosis

Alan Lucks | MD

Medically reviewed by Alan Lucks | MD, Alan Lucks MDPC Private Practice - New York on January 20th, 2024.

Key Takeaways

  • Post-exertional malaise (PEM) is the hallmark symptom—physical or mental activity that was previously tolerated now causes a worsening of symptoms lasting 24+ hours, distinguishing it from normal fatigue.
  • Diagnosis requires extreme fatigue lasting at least 6 months plus at least four additional symptoms: unrefreshing sleep, cognitive impairment ("brain fog"), muscle pain, joint pain, sore throat, tender lymph nodes, or new headaches.
  • The condition affects 836,000 to 2.5 million Americans, with women 2-4 times more likely to be affected than men, and onset often follows viral infections like Epstein-Barr virus, COVID-19, or mononucleosis.
  • No laboratory test can diagnose the condition—doctors must rule out other causes like thyroid disorders, sleep apnea, and depression through blood work and clinical evaluation.
  • Activity pacing is the most evidence-based management strategy, involving staying within your "energy envelope" rather than pushing through symptoms, as overexertion typically worsens the condition long-term.

Chronic Fatigue Syndrome, also known as Myalgic Encephalomyelitis (CFS/ME), is a complex condition characterized by extreme fatigue that doesn't improve with rest. Unlike normal fatigue, CFS/ME can significantly impact your daily life, making it difficult to perform everyday tasks at home and work.

Symptoms of Chronic Fatigue Syndrome

The main symptom of CFS/ME is a new onset of fatigue that lasts for at least six months. Other common symptoms include:

  • Post-exertional malaise: Feeling worse after physical activity, often the next day

  • Unrefreshing sleep: Waking up feeling unrefreshed, despite getting enough sleep

  • Cognitive difficulties: Trouble concentrating and multi-tasking

  • Orthostatic intolerance: Feeling lightheaded or experiencing a rapid heartbeat when standing up

CFS/ME often involves cycles of flare-ups and remissions, with good days and bad days. However, even on good days, you may not feel completely back to normal.

Understanding Chronic Fatigue Syndrome (CFS/ME): Symptoms, Causes, and Diagnosis

How Common is Chronic Fatigue Syndrome?

According to the Centers for Disease Control and Prevention (CDC), up to 2.5 million Americans may have CFS/ME. The condition can affect anyone, including children and teens, but is most common in women in their 40s and 50s. Women are more likely to develop CFS/ME than men.

Potential Causes of Chronic Fatigue Syndrome

The exact cause of CFS/ME is unknown, but researchers have identified several potential contributing factors:

  • Immune system abnormalities

  • Impaired energy production in cells

  • Brain abnormalities, such as changes in brain hormones or electrical activity

  • Blood pressure and heart rate irregularities

  • Genetic factors

  • Infections or other illnesses, such as Epstein-Barr virus, Lyme disease, or Q fever

  • Imbalances in brain chemicals, like serotonin, and hormones, like cortisol

Diagnosing Chronic Fatigue Syndrome

Diagnosing CFS/ME can be challenging, as there is no specific diagnostic test for the condition. The National Academy of Medicine has issued guidelines describing the combination of symptoms necessary for a CFS/ME diagnosis. However, because extreme fatigue is a symptom of many other conditions, your doctor will likely want to rule out other potential causes before considering a CFS/ME diagnosis.

If you suspect you may have CFS/ME, it's essential to consult with your healthcare provider and discuss all of your symptoms. A complete checkup can help rule out other conditions and guide your doctor in determining the most appropriate diagnosis and treatment plan. For more information on living with and managing CFS/ME, visit the CDC's resources on living with ME/CFS.

The Bottom Line

Early recognition and proper pacing are crucial since pushing through symptoms often leads to significant setbacks and worsening disability. The key is learning to manage energy levels within your current capacity rather than trying to "exercise your way out" of the condition. If you're experiencing persistent fatigue with post-exertional malaise, Doctronic can help evaluate your symptoms and guide appropriate next steps.

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