Reye's syndrome is a serious condition that causes swelling in the liver and brain. It can occur at any age but usually affects children and teenagers after a viral infection, most commonly the flu or chickenpox. Reye's syndrome is rare. The condition also is known as Reye syndrome.

Symptoms such as confusion, seizures and loss of consciousness need emergency treatment. Early diagnosis and treatment of Reye's syndrome can save a child's life.

Aspirin has been linked with Reye's syndrome in children or teenagers who have the flu or chickenpox. Do not give children or teenagers aspirin. To treat fever or pain, consider giving your child infants' or children's acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others). Infants' or children's acetaminophen and ibuprofen medicines are safer alternatives to aspirin. Talk to your healthcare professional if you have concerns.

The symptoms of Reye's syndrome usually start about 3 to 5 days after a viral infection begins. The viral infection may be the flu, also known as influenza, or chickenpox. Or Reye's syndrome may develop after an upper respiratory infection such as a cold.

In Reye's syndrome, a child's blood sugar usually drops while levels of ammonia and acidity in the blood rise. The liver also may swell, and fats may build up. Swelling may occur in the brain. This can cause seizures, convulsions or loss of consciousness.

Initial symptoms

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

• Diarrhea.
• Rapid breathing.

For older children and teenagers, early symptoms may include:

• Vomiting that doesn't stop.
• Being sleepy or sluggish.

Additional symptoms

As the condition gets worse, symptoms may become more serious, including:

• Irritable, aggressive or irrational behavior.
• Confusion or seeing or hearing things that aren't there.
• Weakness in the arms and legs or not being able to move them.
• Seizures.
• Excessive sluggishness.
• Decreased level of consciousness.

These symptoms need 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.
• Loses consciousness.

Contact your child's healthcare professional if your child experiences the following symptoms after having the flu or chickenpox:

• Vomits repeatedly.
• Becomes unusually sleepy or sluggish.
• Has sudden behavior changes.

The exact cause of Reye's syndrome is not known. The use of aspirin during a viral illness has most commonly been linked to Reye's syndrome. Several factors may play a role.

In some children, the symptoms of Reye's syndrome may be caused by another health condition, such as a metabolic condition. This can occur even without the use of aspirin.

Metabolic conditions are rare. The most common condition that causes Reye's syndrome is medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. In MCAD deficiency, the body can't break down certain fats to turn them into energy. This happens because an enzyme is missing or not working properly. MCAD deficiency is a fatty acid oxidation disorder.

In people with a fatty acid oxidation disorder, aspirin use during a viral illness is more likely to trigger symptoms of Reye's syndrome. A screening test can determine if your child has a fatty acid oxidation disorder.

Reye's syndrome may develop after influenza or chickenpox in particular.

Exposure to certain toxins — such as insecticides, herbicides and paint thinner — may produce symptoms similar to Reye's syndrome. But these toxins don't cause Reye's syndrome.

The following risk factors — usually when they occur together — may lead to Reye's syndrome:

• Using aspirin to treat a viral infection such as chickenpox, the flu or an upper respiratory infection.
• Having a metabolic condition. This may include a fatty acid oxidation disorder.

Most children and teenagers who have Reye's syndrome survive. However, varying degrees of lasting brain damage are possible. Without proper diagnosis and treatment, Reye's syndrome can cause death within a few days.

To prevent Reye's syndrome, do not give children or teenagers aspirin. This includes plain aspirin and medicines that contain aspirin. Aspirin has been linked to Reye's syndrome in children and teenagers who have the flu or chickenpox.

Some hospitals and medical facilities screen newborns for fatty acid oxidation disorders to determine which children are at greater risk of developing Reye's syndrome. It's especially important not to give aspirin or medicines that contain aspirin to children with known fatty acid oxidation disorders.

Always check the label before you give your child medicine. This includes products you buy without a prescription and alternative or herbal remedies. Aspirin can show up in some unexpected products such as Alka-Seltzer.

Sometimes aspirin goes by other names, such as:

• Acetylsalicylic acid.
• Acetylsalicylate.
• Salicylic acid.
• Salicylate.

For the treatment of fever or pain related to the flu, chickenpox or another viral illness, give your child a safer alternative to aspirin. This may include infants' or children's acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others).

There's an exception to the general rule about aspirin. Children and teenagers who have certain chronic diseases, such as Kawasaki disease, may need long-term treatment with medicines that contain aspirin.

If your child needs to take aspirin, make sure your child's vaccines are current. This includes two doses of the chickenpox vaccine and a yearly flu vaccine. Avoiding these two viral illnesses can help prevent Reye's syndrome.

Treatment for Reye's syndrome usually is done in the hospital. Serious symptoms may be treated in the intensive care unit. Healthcare professionals closely monitor your child's blood pressure and other vital signs. Specific treatment may include:

• Intravenous (IV) fluids. Sugar — also called glucose — and an electrolyte solution may be given through an IV line.
• Diuretics. These medicines may be used to decrease pressure from fluids around the brain. Diuretics also increase fluid loss through urination.
• Medicines to prevent bleeding. Bleeding due to liver problems may require treatment with vitamin K, plasma and platelets.
• Cooling blankets. These blankets help maintain internal body temperature at a safe level.

A breathing machine called a ventilator can help if your child has trouble breathing.

Reye's syndrome is often diagnosed in an emergency situation. This is because of the serious symptoms caused by Reye's syndrome, including seizures or loss of consciousness. Sometimes early symptoms may prompt an appointment with a healthcare professional.

Your child is likely to be referred to a specialist in conditions of the brain and nervous system, known as a neurologist.

Here are some tips to help you get ready for your appointment.

What you can do

• Be aware of any pre-appointment restrictions. At the time you make the appointment, ask if there's anything you need to do in advance.
• Write down any symptoms your child is experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Make a list of all medicines. Include vitamins, dietary supplements and medicines you can buy without a prescription that your child has taken. Be sure to list any medicines containing aspirin. Even better, take the original bottles and a written list of the doses and directions.
• Take along a family member or friend. It can be hard to recall all the information provided to you during an appointment. A friend or family member may remember something that you forgot or missed.
• Write down questions to ask your healthcare professional. Don't be afraid to ask questions or to speak up when you don't understand something.

List your questions from most important to least important to make the most of your time. For Reye's syndrome, some basic questions to ask 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 pluses and minuses for each?
• What results can I expect?
• What kind of follow-up should I expect?

In addition to the questions that you've prepared, don't hesitate to ask other questions during your appointment.

What to expect from your doctor

The neurologist is likely to ask about your child's symptoms and history of viral illnesses. The neurologist may do a medical exam and schedule tests to gather information about your child's condition. Tests also may rule out other diseases, such as meningitis or encephalitis.