Most people with viral encephalitis have either no symptoms or mild flu-like symptoms, such as the following:

  • Headache
  • Fever
  • Aches in muscles or joints
  • Fatigue or weakness

More-serious cases require prompt medical care. Signs and symptoms may include the following:

  • Severe headache
  • Fever
  • Altered consciousness
  • Confusion or agitation
  • Personality changes
  • Seizures
  • Loss of sensation or paralysis in certain areas of the body
  • Muscle weakness
  • Hallucinations
  • Double vision
  • Perception of foul smells
  • Problems with speech or hearing
  • Loss of consciousness

Signs and symptoms in infants and young children may also include:

  • Bulging in the soft spots (fontanels) of the skull in infants
  • Nausea and vomiting
  • Body stiffness
  • Constant, inconsolable crying
  • Crying that worsens when the child is picked up
  • Poor feeding

When to see a doctor

Get immediate care if you or someone you know is experiencing any of the symptoms associated with more-severe cases of encephalitis. Severe headache, fever and altered consciousness — almost always present with encephalitis in older children and adults — require urgent care.

Infants and young children with any signs or symptoms of encephalitis should receive urgent care.

May. 05, 2011