Overview
Reye’s syndrome is a rare but serious condition that causes swelling in the liver and brain. Reye’s syndrome most often occurs in children and teenagers recovering from a viral infection, most commonly the flu or chickenpox.
Signs and symptoms such as confusion, seizures and loss of consciousness require emergency treatment. Early diagnosis and treatment of Reye’s syndrome can save a child’s life.
Aspirin has been linked with Reye’s syndrome, so use caution when giving aspirin to children or teenagers for fever or pain. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin.
For the treatment of fever or pain, consider giving your child infants’ or children’s over-the-counter fever and pain medications such as acetaminophen (Tylenol, other brands) or ibuprofen (Advil, Motrin, other brands) as a safer alternative to aspirin. Talk to your doctor if you have concerns.
Symptoms of Reye’s syndrome
In Reye’s syndrome, a child’s blood sugar level typically drops while the levels of ammonia and acidity in the 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 the onset of a viral infection, such as the flu 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 this 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 do you need 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, you must 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 symptoms after a bout with the flu or chickenpox:
- Vomits repeatedly
- Becomes unusually sleepy or lethargic
- Has sudden behavior changes
What cause Reye’s syndrome ?
The exact cause of Reye’s syndrome is unknown, although several factors may play a role in its development. Reye’s syndrome seems to be triggered by using aspirin to treat a viral illness or infection — particularly flu and chickenpox — in children and teenagers who have an underlying fatty acid oxidation disorder.
Fatty acid oxidation disorders are a group of inherited metabolic disorders in which the body is unable to break down fatty acids because an enzyme is missing or not working properly. A screening test is needed to determine whether your child has a fatty acid oxidation disorder or not.
In some cases, the symptoms and signs of Reye’s syndrome may be duplicated by an underlying metabolic condition unmasked by a viral illness. The most frequent disorder of these rare disorders is medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. Exposure to certain toxins — such as insecticides, herbicides and paint thinner — may produce symptoms similar to those of Reye’s syndrome, but these toxins don’t cause Reye’s syndrome.
Risk factors
The following factors — usually when they occur together — may increase a child’s risk of developing Reye’s syndrome:
- Using aspirin to treat a viral infection, such as flu, chickenpox or an upper respiratory infection
- Having an underlying fatty acid oxidation disorder
Complications of Reye’s syndrome
Most children and teenagers who have Reye’s syndrome survive, although varying degrees of permanent brain damage are possible. Without proper diagnosis and treatment, Reye’s syndrome can be fatal within a few days.
Prevention of Reye’s syndrome
Use caution when giving aspirin to children or teenagers. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. These medications include plain aspirin and medications that contain aspirin.
Some hospitals and medical facilities conduct newborn screenings for fatty acid oxidation disorders to determine which children are at greater risk of developing Reye’s syndrome. Children with known fatty acid oxidation disorders should not take aspirin or aspirin-containing products.
Always check the label before you give your child medication, including over-the-counter products and alternative or herbal products. Aspirin can show up in some unexpected products, such as Alka-Seltzer.
Sometimes aspirin appears under other names, too, such as:
- Acetylsalicylic acid
- Acetylsalicylate
- Salicylic acid
- Salicylate
For the treatment of fever or pain related to the flu, chickenpox or another viral illness, consider giving your child infants’ or children’s over-the-counter fever and pain medications such as acetaminophen (Tylenol, other brands) or ibuprofen (Advil, Motrin, other brands) as a safer alternative to aspirin.
There’s one caveat to the aspirin rule, however. Children and teenagers who have certain chronic diseases, such as Kawasaki disease, may need long-term treatment with drugs that contain aspirin.
If your child needs aspirin therapy, make sure your child’s vaccines are current — including two doses of the varicella (chickenpox) vaccine and a yearly flu vaccine. Avoiding these two viral illnesses can help prevent Reye’s syndrome.
Diagnosis of Reye’s syndrome
There’s no specific test for diagnosing Reye’s syndrome. Instead, screening for Reye’s syndrome usually begins with blood and urine tests as well as testing for fatty acid oxidation disorders and other metabolic disorders.
Sometimes more-invasive diagnostic tests are needed to evaluate other possible causes of liver problems and investigate any neurological abnormalities. For example:
- Lumbar puncture. Lumbar puncture can help the doctor identify or rule out other diseases with similar signs and symptoms, such as infection of the lining that surrounds the brain and spinal cord (meningitis) or inflammation or infection of the brain (encephalitis).
During lumbar puncture, a needle is inserted through the lower back into a space below the end of the spinal cord. A small sample of cerebrospinal fluid is taken and sent to a lab for analysis.
- Liver biopsy. A liver biopsy can help the doctor identify or rule out other conditions that may be affecting the liver.
During a liver biopsy, a needle is inserted through the skin on the upper right side of the abdomen and into the liver. A small sample of liver tissue is taken and sent to a lab for analysis.
- Computerized tomography (CT) scan or magnetic resonance imaging (MRI). A head CT or MRI scan can help the doctor identify or rule out other causes of behavior changes or decreased alertness.
A CT scan uses a sophisticated imaging machine linked to a computer to produce detailed images of the brain. An MRI scan uses a strong magnetic field and radio waves rather than X-rays to generate images of the brain.
- Skin biopsy. Testing for fatty acid oxidation disorders or metabolic disorders may require a skin biopsy, although direct gene sequencing together with blood and urine tests are often sufficient to make such a diagnosis.
During a skin biopsy, a doctor takes a small skin sample for analysis in a lab. A biopsy can usually be done in a doctor’s office using a local anesthetic.

Preparing for an appointment with a doctor
Reye’s syndrome is often diagnosed in an emergency situation because of serious signs and symptoms, such as seizures or loss of consciousness. In some cases, early signs and symptoms prompt a doctor’s appointment.
You’ll likely be referred to a doctor who specializes in conditions of the brain and nervous system (neurologist).
You should prepare carefully for the appointment with your doctor. Here are some tips to help you get ready.
What you can do to prepare
- Be aware of any pre-appointment restrictions. At the time you make the appointment, ask whether there’s anything you need to do in advance.
- Write down any symptoms your child is experiencing, including any symptom that may seem unrelated to the reason for which you scheduled the appointment.
- Make a list of all medications, including vitamins, dietary supplements and over-the-counter drugs, that your child has taken, especially any product containing aspirin. You should take the original bottles and a written list of the medication dosages and directions.
- Take a family member or friend along with you. It can be difficult to recall all the information provided to you during an appointment. The person who accompanies you may remember something that you forgot or missed.
- Write down questions to ask the doctor. Don’t be afraid to ask questions or to speak up when you don’t understand something the doctor says.
List your questions from most important to least important in case your time with your doctor runs out. For Reye’s syndrome some basic questions to ask your doctor include:
- What are other possible causes for my child’s symptoms?
- What tests are needed to confirm the diagnosis?
- What are the treatment options and the pros and cons for each option?
- What results can I expect?
In addition to the questions that you’ve prepared to ask the doctor, don’t hesitate to ask other questions during your appointment.
What the doctor will ask
The neurologist is likely to ask about your child’s symptoms and history of viral illnesses. The doctor will also conduct a medical exam and schedule tests to gather information about your child’s condition and to rule out other diseases, such as meningitis or encephalitis.
Treatment of Reye’s syndrome
Reye’s syndrome is usually treated in the hospital. Severe cases may be treated in the intensive care unit. The hospital staff will closely monitor your child’s blood pressure and other vital signs. Specific treatment may include:
- Intravenous fluids. Glucose and an electrolyte solution may be given through an intravenous line.
- Diuretics. These medications may be used to decrease intracranial pressure and increase fluid loss through urination.
- Medications to prevent bleeding. Bleeding due to liver abnormalities may require treatment with vitamin K, plasma and platelets.
- Cooling blankets. This intervention helps maintain internal body temperature at a safe level.
If your child has trouble breathing, your child may need assistance from a breathing machine (ventilator).