Chronic fatigue syndrome (CFS) is an illness characterized by persistent and severe fatigue that affects daily life and activities. It can be difficult to diagnose CFS as there is no single test to determine if one has the condition. Symptoms of CFS can include extreme exhaustion, muscle aches, difficulty concentrating, and difficulty sleeping. People with CFS may also experience a wide variety of other symptoms, such as headaches, joint pain, and cognitive problems. To determine if you have CFS, your doctor will likely evaluate your medical history, perform a physical examination, and ask about your symptoms. If your doctor suspects CFS, they may order tests to rule out other possible conditions. It is important to consult your doctor if you think you may have CFS, as early diagnosis and treatment can help manage symptoms and improve quality of life.