In Reye's syndrome, a child's blood sugar level typically drops while the levels of ammonia and acidity in his or her blood rise. At the same time, the liver may swell and develop fatty deposits. Swelling may also occur in the brain, which can cause seizures, convulsions or loss of consciousness.

The signs and symptoms of Reye's syndrome typically appear about three to five days after a viral infection, such as the flu (influenza) or chickenpox, or an upper respiratory infection, such as a cold.

Initial signs and symptoms

For children younger than age 2, the first signs of Reye's syndrome may include:

  • Diarrhea
  • Rapid breathing

For older children and teenagers, early signs and symptoms may include:

  • Persistent or continuous vomiting
  • Unusual sleepiness or lethargy

Additional signs and symptoms

As the condition progresses, signs and symptoms may become more serious, including:

  • Irritable, aggressive or irrational behavior
  • Confusion, disorientation or hallucinations
  • Weakness or paralysis in the arms and legs
  • Seizures
  • Excessive lethargy
  • Decreased level of consciousness

These signs and symptoms require emergency treatment.

When to see a doctor

Early diagnosis and treatment of Reye's syndrome can save a child's life. If you suspect that your child has Reye's syndrome, it's important to act quickly.

Seek emergency medical help if your child:

  • Has seizures or convulsions
  • Loses consciousness

Contact your child's doctor if your child experiences the following after a bout with the flu or chicenpox:

  • Vomits repeatedly
  • Becomes unusually sleepy or lethargic
  • Has sudden behavior changes
Sep. 17, 2011