Diagnosing chronic fatigue syndrome (CFS) is difficult because its symptoms can overlap with those of other illnesses, including anxiety disorders, depression, and other conditions of psychiatric origin. A person may be diagnosed with CFS if he or she has chronic fatigue for more than six months along with at least four other symptoms of chronic fatigue syndrome. Doctors diagnosing chronic fatigue syndrome will usually review the patient's medical history, conduct physical and mental status examinations, and perform lab tests (including blood and urine tests).