©2018 WebMD, Inc. All rights reserved. eMedicineHealth does not provide medical advice, diagnosis or treatment. See Additional Information.

Symptoms and Signs of Encephalitis

Doctor's Notes on Encephalitis

Encephalitis is inflammation of the brain. Encephalitis is not the same as meningitis, which is inflammation of the membranes covering the brain. Both of the diseases may be present at the same time, and both conditions share many of the same symptoms so they may be difficult to distinguish. Causes of encephalitis include viruses, bacteria, parasites, chemicals, and even autoimmune reactions.

Symptoms of encephalitis may last for two to three weeks, are flu-like, and may include fever, fatigue, muscle weakness, rhythmic muscle contractions, muscle pain, sore throat, stiff neck and back, loss of appetite, nausea, vomiting, headache, confusion, irritability, unsteady gait, weakness, problems with coordination, drowsiness, and visual sensitivity to light. Symptoms of encephalitis in infants may also include poor feeding, irritability, vomiting, bulging fontanel, and body stiffness. Symptoms of severe cases of encephalitis may include seizures, muscle weakness, paralysis, memory loss, impaired judgment, delirium and/or hallucinations, disorientation, poor responsiveness, or altered level of consciousness

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/11/2019


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.