Postviral syndrome refers to the health condition that occurs after a person has recovered from a viral infection. Also known as post-infectious fatigue syndrome or myalgic encephalomyelitis, the syndrome causes persistent exhaustion, muscle and joint pains, and brain fog. Some synonyms to describe postviral syndrome include chronic fatigue syndrome, post-viral fatigue syndrome, and post-infectious illness. Other names used to refer to the condition include chronic infectious mononucleosis, chronic Epstein-Barr virus, and chronic fatigue and immune dysfunction syndrome. The symptoms of postviral syndrome can last for several months to years, and treatment usually involves lifestyle changes, medication, and therapy.