Reye's Syndrome

In the 1960s and 1970s, as many as 500 children in the United States per year were affected by Reye's syndrome, a serious, often fatal disorder.

Sick girl in bed comforted by mother
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It is still not known exactly what causes Reye's syndrome (RS) to develop, but research has shown an association between the development of the syndrome and the use of aspirin (salicylates) to treat upper respiratory illness (e.g. flu, cold) and chicken pox. RS is not contagious.

The number of cases of RS reported has dropped to less than 2 cases per year, due to vaccines and educational campaigns that resulted in a decreased use of aspirin products to treat children’s illnesses. More cases of RS occur during flu season — the months of January, February, and March. Most of those affected by RS are children below age 15, but rarely it may affect older adolescents, and even young adults.

Attacks the Liver and Brain

Reye's syndrome affects many organs in the body, but particularly the liver and brain. It causes damage to the cells in the liver, especially targeting mitochondira. As a result, ammonia builds up in the blood , causing brain swelling and injury (encephalopathy).


Usually, the flu, viral illness, or chickenpox is almost over, and the child is starting to recover when the symptoms of Reye's syndrome begin:

First stage:

  • Loss of energy, lethargy
  • Nausea and vomiting
  • Drowsiness

Second stage:

  • Personality changes such as irritability, aggressive behavior
  • Restless, confused, disoriented
  • Drowsiness and deep lethargy may change to unconsciousness (coma)
  • Hyperventilation, tachycardia

Third Stage:

  • Unconsciousness, light coma

Fourth Stage:

  • Deepening coma, seizures, rigidity, unresponsive pupils

Fifth Stage:

  • Seizures, deep coma, flaccid paralysis, rigidity, unresponsive pupils, respiratory arrest, fixed, dilated pupils, death


The diagnosis of Reye's syndrome is based on the child having had a viral illness (especially if treated with aspirin), plus the current symptoms the child is having. Special blood tests for ammonia level, liver function, and other parameters assist in making the diagnosis.

Many types of illnesses and disorders have symptoms similar to Reye's syndrome, so medical providers may diagnose the symptoms as something else. At first, a physician may suspect meningitis, encephalitis, diabetes, poisoning, or mental illness. One important clue to Reye's syndrome is the viral illness that was present before the symptoms started.


Reye's syndrome is a serious illness. As many as 50 percent of individuals who develop the syndrome die from it. The individual with Reye's syndrome needs intensive care to reduce the brain swelling quickly to prevent permanent brain damage, and to prevent other complications from the disorder. Early diagnosis and prompt treatment will improve the individual’s prognosis.


Since the use of aspirin and aspirin-containing products is associated with increased risk of Reye's syndrome, The National Reye's Syndrome Foundation, the Surgeon General, the FDA, and the CDC recommend that those medicines not be given to children or teenagers who have the flu or chicken pox.

You may recognize some brands, such as Bayer or St. Joseph, as aspirin, but there are other products that contain aspirin, such as Anacin, Excedrin, Dristan, and Pamprin or contain chemicals like aspirin, such as in Pepto-Bismol. If you aren’t sure if something contains aspirin, ask your healthcare provider or pharmacist. The National Reye’s Syndrome Foundation also has a list of ingredients to avoid (products containing salicylates) that can help you.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Organization for Rare Disorders. Reye syndrome.

  2. Belay ED, Bresee JS, Holman RC, Khan AS, Shahriari A, Schonberger LB. Reye’s Syndrome in the United States from 1981 through 1997N Engl J Med. 1999;340(18):1377-1382. doi:10.1056/NEJM199905063401801

  3. Reye's Syndrome Foundation. What is Reye's syndrome?

  4. Chapman J, Arnold JK. Reye syndrome. In: Stat Pearls [online].

  5. Cleveland Clinic. Reye's syndrome.

  6. Lovejoy FH, Smith AL, Bresnan MJ, et al. Clinical staging in Reye syndromeAm J Dis Child. 1974;128:36-41. doi:10.1001/archpedi.1974.02110260038007

  7. Centers for Disease Control and Prevention. Surgeon General's advisory on the use of salicylates and Reye syndrome. Morb Mortal Wkly Rep. 1982;31(22);289-290.

By Mary Kugler, RN
Mary Kugler, RN, is a pediatric nurse whose specialty is caring for children with long-term or severe medical problems.