Reye's syndrome

12 min read

What is Reye's syndrome?

Reye's syndrome is a rare condition that causes serious liver and brain damage. If it is not treated promptly it may result in permanent brain injury or death.

Most recorded cases of Reye's syndrome happen in children, but adult cases have also occurred.

Symptoms can include:

  • persistent vomiting
  • loss of energy
  • changing mood, such as irritability or severe confusion and anxiety (delirium)
  • drowsiness and eventually

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symptoms of Reye's syndrome

What causes Reye's syndrome?

The exact cause of Reye's syndrome is unknown, but most cases have been in children recovering from a viral infection, such as

(flu) or
, and in many of these cases the child had previously taken
to treat their symptoms.

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causes of Reye's syndrome

Due to the possible link between Reye's syndrome and aspirin, the medicines watchdog, the Medicines and Healthcare products Regulatory Agency (MHRA), recommends children under 16 years old should not take aspirin unless advised to do so by a doctor.

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preventing Reye's syndrome

Who is affected?

Since health warnings were issued in the late 1980s about not giving aspirin to children, the number of cases of Reye's syndrome has fallen dramatically.

Despite the decrease, some healthcare professionals believe a large flu pandemic (a global outbreak of a new strain of the flu virus) may lead to an upsurge in cases of Reye's syndrome, particularly if parents ignore the warning about aspirin.

Reye's syndrome affects boys and girls, and all races, equally.

Treating Reye's syndrome

Reye's syndrome should be treated as a medical emergency because it can rapidly damage the liver and brain. A child with Reye's syndrome will need to be taken immediately to an intensive care unit so their body's functions can be supported while they are receiving treatment.

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treating Reye's syndrome

As a result of advances in diagnosing and treating Reye's syndrome, it is now estimated that eight out of 10 people who develop the condition will survive. However, children can sometimes develop a degree of brain damage after recovering from Reye's syndrome.

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complications of Reye’s syndrome

Reye's syndrome symptoms

The symptoms of Reye's syndrome usually begin a few days after a child develops a viral infection.

Initial symptoms of Reye's syndrome include:

  • persistent, effortless vomiting
  • listlessness (a lack of interest or enthusiasm)
  • loss of energy
  • drowsiness

As Reye's syndrome progresses, the symptoms may become more severe and wide ranging, and can include:

  • extreme irritability
  • agitation
  • delirium (a severe state of mental confusion and anxiety sometimes associated with hallucinations)
  • coma

When to seek medical advice

You should always contact your doctor if your child:

  • vomits persistently
  • appears unusually drowsy and listless

Although these symptoms will probably not be the result of Reye's syndrome, they still need to be checked by your doctor.

If you cannot get hold of your doctor, visit the nearest accident and emergency department.

Reye's syndrome causes

The exact cause of Reye's syndrome is unknown, but most experts agree that a previous viral infection and the use of aspirin are important factors.

For example, the condition has occurred in children who have been treated with

for a viral infection such as:

Genetic factors

It is possible genetic (inherited) factors could play a role in Reye's syndrome. For example, a child may be born with an as yet unknown genetic predisposition (tendency) that makes Reye's syndrome more likely.

If this child then has a viral infection and takes aspirin, or one of the active ingredients in aspirin, such as salicylate, this can trigger the condition.

The effects of Reye's syndrome

Reye's syndrome is thought to damage part of a human cell known as the mitochondrion. Mitochondria provide human cells with energy.

Mitochondria are particularly important for the healthy functioning of the liver. The liver depends on mitochondria to provide energy for many of its vital functions, such as filtering toxins (poisons) from the blood and regulating blood sugar levels.

Once the liver loses its energy supply, it begins to fail. This will result in a dangerous build-up of toxic chemicals in the blood, such as ammonia, which will damage the entire body. It is the loss of liver function that causes the symptoms of vomiting, tiredness and a lack of energy.

The rapid loss of liver function causes the brain to swell, leading to the changes in mental state associated with Reye's syndrome, such as confusion and delirium.

Reye's syndrome diagnosis

See your doctor immediately or visit the nearest accident and emergency department if you think your child may have Reye's syndrome.

If your child has taken

, inform your doctor or the healthcare professionals that treat your child.

Ruling out other conditions

As Reye's syndrome is such a rare condition, the first stage of diagnosis is to rule out other conditions that can cause similar symptoms. For example:

  • meningitis
    – an infection of the meninges (the protective membranes that surround the brain and spinal cord)
  • blood poisoning
    – a bacterial infection of the blood
  • encephalitis
    – inflammation of the brain

Inherited metabolic disorders

An inherited metabolic disorder affects the chemical reactions taking place in your body. If you have a defect in one of these chemical reactions, it can cause a build-up of one type of chemical and a shortage of another type of chemical, leading to symptoms similar to those of Reye's syndrome.

The build-up of a chemical can have a toxic effect. Or you may have a shortage of a chemical vital for your normal body functions. It is therefore important that the correct diagnosis is made so that appropriate treatment can be started as soon as possible.

There will also be long-term implications for the management of the condition, such as dietary restrictions, in order to prevent further 'Reye-like' episodes occurring.

Genetic counselling
may be recommended, as future pregnancies or existing siblings may be affected.

The most common example of one of these inherited metabolic disorders is

medium chain acyl dehydrogenase deficiency (MCADD)


During the first stage of diagnosis,

blood tests
and urine tests should be carried out to determine whether there is a build-up of toxins or bacteria in the blood, and to check whether the liver is functioning normally.

Special tests may be undertaken to measure the presence or absence of certain chemicals that could indicate an inherited metabolic disorder rather than Reye's syndrome.

Other tests that may be recommended include:

These procedures are briefly described below.

CT scan

A computerised tomography (CT) scan, which produces detailed images of the body, may be used to check the pressure level in the brain.

Lumbar puncture

The CT scan may be followed by a lumbar puncture. This involves taking a sample of cerebrospinal fluid (CSF) from the base of the spine and checking to see if it has bacteria or viruses. CSF is the fluid that surrounds and protects the brain and spinal cord.

A lumbar puncture is useful for ruling out meningitis or encephalitis. However, paediatricians (specialists in conditions affecting children) will be cautious about doing a lumbar puncture if they think the child may have brain swelling.


Finally, a liver biopsy may be done. This involves taking a small sample of the liver so it can be closely examined under a microscope. Reye's syndrome causes distinctive changes to the cells of the liver, which can be detected using a biopsy.

Treatment for Reye's syndrome

Treatment for Reye's syndrome will require immediate admission to an intensive care unit (ICU).

The aim of treatment is to minimise the symptoms of Reye's syndrome and support your child's vital functions, such as their breathing and blood circulation. It is also essential to protect your child's brain against permanent damage, which the brain swelling can cause.

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intensive care

Possible medicines

Your child may be given medicines intravenously (directly into a vein). Possible medications include:

  • chemicals and fluids – to correct blood chemistry and supply nutrients, such as glucose (sugar)
  • diuretics – medication to help rid the body of excess fluid and reduce swelling in the brain
  • ammonia detoxicants – medication that reduces the level of ammonia (a toxic chemical produced by the body) in order to prevent it damaging the body
  • antiemetic medication – anti-sickness medication to help prevent or reduce vomiting (although by the time a child is admitted to hospital they have usually stopped being sick)


Your child's vital functions will also be closely monitored, including:

  • their heart and pulse rate
  • the air flow to their lungs
  • their blood pressure and blood flow
  • the pressure in their veins, known as central venous pressure (CVP)
  • the amount of oxygen in their blood
  • their body temperature
  • their urine output

A ventilator (breathing machine) may be used if the symptoms of Reye's syndrome become severe and your child needs help with their breathing.

Once the swelling of your child's brain has decreased, the rest of their body's functions should return to normal within a few days. However, it may be several weeks before your child is well enough to leave hospital.


You should not give aspirin (acetylsalicylic acid) or medicines that contain aspirin to children under 16 years old, unless a doctor specifically advises you to do so.

You should also not give the following to young children unless advised otherwise by a doctor:

  • acetylsalicylate
  • salicylic acid
  • salicylate
  • salicylate salts – found in Bonjela (a treatment for
    mouth ulcers

Alternatives to aspirin

If your child or teenager has

(influenza) or other viral infections, painkillers such as ibuprofen or paracetamol can reduce their fever and relieve pain. However, ibuprofen is not recommended for those with a history of:

Check with your doctor or pharmacist if you are unsure. You can also read more information about


Conditions that need aspirin

Some children under 16 years old have specific conditions that need to be treated with medication that contains aspirin. For example:

  • Kawasaki disease
    – a condition that causes inflammation of the arteries
  • juvenile arthritis – a rare form of arthritis that affects children

If your child has one of these conditions, your paediatrician may decide the benefits of taking medication containing aspirin outweighs the risks. If your paediatrician advises that your child should take aspirin, they may also recommend the chickenpox and flu (influenza) vaccines to reduce your child's risk of developing Reye's syndrome.

Read more information about chickenpox vaccination and flu vaccination.

Complications of Reye's syndrome

Brain damage is the main complication of Reye's syndrome. However, spending several weeks in hospital may also affect your child both physically and psychologically.

Returning from hospital

For example, after returning home your child may:

Some hospitals offer follow-up clinics or outreach services for people who have been in

intensive care
. The clinics provide an opportunity to discuss the time spent in intensive care with the intensive care doctors and nurses.

If your hospital does not offer this service, you can visit your doctor to discuss any problems that your child is having since their treatment in intensive care.

Brain damage

Brain damage can range from mild to severe. The level of brain damage experienced usually depends on the amount of swelling in the brain. In general, brain damage is more likely if Reye's syndrome was severe.

Specific difficulties associated with brain damage that have occurred in children who have had Reye's syndrome include:

  • poor attention span
  • poor memory
  • some loss of vision
  • some loss of hearing
  • speech and language difficulties
  • problems with motor skills, such as movement, dexterity and posture
  • problems completing tasks
  • difficulty swallowing (
  • difficulty using the toilet
  • difficulty dressing

Living with a disability

If your child has Reye's syndrome and develops a disability as a result, an individual care plan will be drawn up to address any needs or problems they have. As your child gets older, the plan will be reassessed to accommodate necessary changes.

You and your child will also be assigned a key worker who will be the first point of contact between you and various support services. While your child is young, the key worker is likely to be a health visitor. A health visitor is a qualified nurse with extra training who helps families with babies and young children avoid illness.

As your child gets older and their needs become more complex, their key worker is likely to be a social worker. A social worker is someone involved in providing social services. They will be able to give you advice about a variety of practical issues, such as benefits, housing, day care and training.

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.