Reye's Syndrome

Reye’s syndrome is a rare condition that happens in children after a viral infection or illness, especially if they took aspirin (salicylate) to treat their symptoms. Reye’s syndrome targets their brain, blood and liver. Symptoms can be life-threatening if not treated early.


What is Reye’s syndrome?

Reye’s syndrome is a rare condition that causes your brain to swell and your liver to lose function after a viral illness or infection like the flu or chickenpox. It’s most common among children who take aspirin to treat symptoms during a viral infection or illness. The condition develops up to one week after the onset of a viral illness.


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Who does Reye’s syndrome affect?

Reye’s syndrome is primarily a children’s disease, although it can occur at any age. Cases usually happen in the fall and winter seasons and are present in children younger than 18 years old.

How common is Reye’s syndrome?

An estimated two children per year in the United States develop Reye’s syndrome.

The frequency of Reye’s syndrome declined because of heightened awareness of the condition. If your child is sick, don’t give them aspirin to treat their symptoms. Vaccinations for the flu and chickenpox (varicella) are successful at preventing viral infections, which also contributes to a low number of cases each year.


How does Reye’s syndrome affect my child’s body?

After a viral illness or infection, like the flu or chickenpox, your child may show new symptoms up to one week after their primary illness or infection. It’s important that you don’t treat your child’s symptoms with aspirin, which could lead to Reye’s syndrome, without first consulting your healthcare provider.

Since Reye’s syndrome causes pressure to build in your child’s brain, their personality could change suddenly. Your happy child could show a lack of interest in their favorite activities or get angry or bothered by something that normally wouldn’t be a problem. Early signs of Reye’s syndrome, like changes to your child’s mental state, could lead to an early diagnosis and treatment, which leads to the best outcome for their health.

Symptoms and Causes

What are the symptoms of Reye’s syndrome?

Symptoms of Reye’s syndrome range in severity based on how the condition affects your child. The first sign of Reye’s syndrome is a viral infection, like a cold, an upper respiratory infection, the flu or chickenpox. After experiencing symptoms of the viral infection for five to seven days, symptoms of Reye’s syndrome appear, including:

  • Vomiting.
  • Feeling tired or lethargic.
  • Showing anxiety, confusion, becoming easily disoriented or experiencing hallucinations.
  • Personality changes such as agitation, irritability or combativeness.
  • Breathing quickly.

Increased pressure in the skull (intracranial pressure) causes changes in how your child’s brain functions, while also affecting how your child’s liver functions. Severe symptoms of Reye’s syndrome include:

  • Seizures.
  • Coma.
  • Loss of consciousness.
  • Difficulty clotting blood.
  • Excess ammonia in their blood.

If these symptoms are present during or soon after a viral illness, seek medical attention immediately because they are life-threatening.


What causes Reye’s syndrome?

The cause of Reye’s syndrome is unknown.

The condition most often happens after a viral infection or illness in children when they’re given aspirin (salicylates) to treat symptoms. Viral illnesses that could trigger Reye’s syndrome include:

  • Flu.
  • Chickenpox.
  • Respiratory infection.
  • Common cold.

Symptoms of Reye’s syndrome are the result of increased fluid or pressure of brain tissues (cerebral edema) and changes to their liver.

Studies suggest that damaged mitochondria could activate Reye’s syndrome in their liver. Mitochondria is the part of a cell (organelle) that provides energy (adenosine triphosphate) and is also known as “the powerhouse of the cell.” Underactive mitochondria affects liver function, causing symptoms of the condition. The reason for damaged mitochondria is unknown.

Does aspirin cause Reye’s syndrome?

Studies show aspirin (salicylate) may trigger Reye’s syndrome and increases the severity of symptoms. The direct cause of Reye’s syndrome is unknown. Talk to your healthcare provider before giving your child aspirin during a viral illness like the flu. Always read the label on all medications before giving it to your child, to check age requirements and instructions. Talk with your healthcare provider if you have any questions.

What is the process (pathophysiology) associated with Reye’s syndrome?

The exact process (pathophysiology) of how Reye’s syndrome affects your child’s body is unknown.

Studies show that the condition progresses when damaged mitochondria cells pair with a viral illness or infection. Symptoms of Reye’s syndrome increase if aspirin enters their body, which worsens damage to mitochondria. Damaged mitochondria causes levels of ammonia to increase in their blood, followed by swelling of their brain (cerebral edema and intracranial pressure). When the pressure to their brain becomes severe, their kidneys start deteriorating fat tissue (fatty degeneration), and neurons (nerve cells responsible for communicating with your brain) lose function.

Diagnosis and Tests

How is Reye’s syndrome diagnosed?

Healthcare providers might suspect Reye’s syndrome after detecting a viral illness followed by observing symptoms of Reye’s syndrome, like vomiting and changes to your child’s behavior, including becoming easily agitated, confused or disoriented. Diagnostic tests rule out other conditions that have similar symptoms.

Your child’s Reye’s syndrome diagnosis will have a severity level marked by a Roman numeral with I (one) being the least severe and V (five) being the most severe.

What tests diagnose Reye’s syndrome?

Your healthcare provider will offer several tests to confirm your child’s diagnosis. Tests could include:

  • Laboratory tests to check ammonia levels in their blood or a buildup of toxins in their urine.
  • Imaging tests like an MRI or CT scan to view their brain.
  • Liver biopsy.
  • Spinal tap to test cerebrospinal fluid.

Can Reye’s syndrome be misdiagnosed?

Reye’s syndrome shares similar symptoms as many other conditions, and a misdiagnosis is possible but not common. Misdiagnosis might include:

Management and Treatment

How is Reye’s syndrome treated?

Treatment for Reye’s syndrome focuses on protecting your child’s brain by reducing swelling, reversing liver damage and metabolic injury (lack of oxygen in their blood) and preventing lung complications. Treatment could include:

  • Inserting a tube into their windpipe (endotracheal intubation) to increase breathing rate (hyperventilation) or using a ventilator.
  • Keeping their head elevated.
  • Taking medicine to lower ammonia levels in their blood (ammonia detoxicants).
  • Taking medicine to maintain sugar levels in their blood (glucose).
  • Taking vitamin K or receiving plasma transfusions to improve blood clotting.

If your child receives a Reye’s syndrome diagnosis, your healthcare provider will admit them into the intensive care unit immediately to receive treatment. Your child’s care team will monitor your child’s body temperature and all of your child’s vital organs to make sure treatment is effective.

Are there any side effects of the treatment?

Most children diagnosed with Reye’s syndrome make a full recovery. If your child experiences severe brain swelling, they could face side effects, including:

  • Memory loss.
  • Difficulty learning.
  • Loss of vision and hearing.
  • Trouble with speech and language.
  • Difficulty moving and completing everyday tasks like getting dressed.

Specialized care might be necessary to support your child and address their needs as they get older.

How soon after treatment will my child feel better?

After treatment when the swelling in your child’s brain reduces, your child will be on the road to recovery. It could take a few days up to a few weeks until your child is healthy enough to leave the hospital. Your healthcare provider will keep you up to date on the progress of your child’s recovery.


How can I prevent Reye’s syndrome?

As there’s a link between aspirin and Reye’s syndrome, you can prevent the condition by not giving aspirin to children, especially if they’re younger than 16 years old. If your child needs aspirin to treat a condition, don’t give your child aspirin before discussing the intended treatment with your healthcare provider.

Always check labels for age requirements before giving medicine to your child or talk with your healthcare provider to make sure the medicine is safe for your child to take.

Outlook / Prognosis

What can I expect if my child has Reye’s syndrome?

Your child’s prognosis depends on the severity of their diagnosis, specifically the amount of swelling of their brain and how much ammonia is in your child’s blood. If the condition moves rapidly and your child goes into a coma, they’ll have a poor prognosis. If the condition receives treatment early after a diagnosis, the prognosis is excellent.

The fatality rate for children diagnosed with Reye’s syndrome is 21% on average. The fatality rate ranges from less than 2% for children diagnosed with stage I or mild Reye’s syndrome to 80% for children who are in a coma with stage V Reye’s syndrome. Early detection and treatment significantly improves the rate of survival.

Children who experience severe symptoms of Reye’s syndrome may have side effects of the condition that last into adulthood, like brain damage, problems with cognitive development, epilepsy, muscle weakness and nerve damage.

Is there a cure for Reye’s syndrome?

There’s no cure for Reye’s syndrome. Depending on their diagnosis, many children make a full recovery. Treatment reduces symptoms and aims to prevent long-term complications or death.

What research is being done for Reye’s syndrome?

Much of the research on Reye’s syndrome focuses on answering fundamental questions about the condition such as what role aspirin plays in this life-threatening condition. The ultimate goal of research is to improve scientific understanding, diagnosis and medical treatment of Reye’s syndrome.

Living With

When should I see my healthcare provider?

If your child experiences any symptoms of Reye’s syndrome after a viral illness or infection or if your child took aspirin (salicylate) that wasn’t under your healthcare provider’s direction, see your healthcare provider immediately.

When should I go to the ER?

Your child may experience seizures or convulsions where they temporarily lose consciousness, move their arms and legs uncontrollably and show anxiety or confusion. Seizures usually last between 30 seconds and two minutes. If this happens, call 911 immediately or take your child to the emergency room.

What questions should I ask my doctor?

  • Will my child experience any symptoms of Reye’s syndrome after they leave the hospital?
  • How will a Reye’s syndrome diagnosis affect my child’s future?
  • What types of medication shouldn’t I give my child if they’re sick?

Additional Common Questions

Can one dose of Pepto-Bismol® cause Reye’s syndrome?

Aspirin (salicylate) is present in Pepto-Bismol® and children should not take it without first consulting their healthcare provider. Aspirin given during a viral illness or infection, like the flu, can cause symptoms of Reye’s syndrome, but the direct cause of Reye’s syndrome is unknown. Always read the label on medicine before giving it to your child or consult your pharmacist or healthcare provider before you give a dose of aspirin to your child.

A note from Cleveland Clinic

Understanding the signs of Reye’s syndrome and taking your child to see their healthcare provider quickly can lead to a positive outcome if you notice changes to your child’s behavior and new symptoms arising after a viral infection or illness. Make sure your child receives their vaccinations on schedule to avoid viral illnesses, especially during the fall and winter seasons. Your child’s care team will keep you up to date on the progress of their health and offer support if your child receives a Reye’s syndrome diagnosis.



U.S. Food and Drug Administration (FDA)

U.S. Department of Health and Human Services

5600 Fishers Lane, CDER-HFD-240

Rockville, MD 20857

Phone: 301.827.4573

Toll-free: 888.INFO.FDA (463.6332)

Website: www.fda.gov

National Reye's Syndrome Foundation

P.O. Box 829

426 North Lewis

Bryan, OH 43506-0829

Phone: 419.636.2679

Toll-free: 800.233.7393

Fax: 419.636.9897

Email: nrsf@reyessyndrome.org

Website: www.reyessyndrome.org

Source: National Institutes of Health; National Institute of Neurological Disorders and Stroke

Medically Reviewed

Last reviewed on 02/25/2022.

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