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Reye's syndrome

Page last reviewed: 13/07/2011

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

Almost all recorded cases of Reye's syndrome have happened in children, but adult cases have also occurred.

The exact cause of Reye's syndrome is unknown, but there is evidence that two factors may contribute towards children developing the condition. These are listed below.

  • Previous viral infection - most children who developed Reye's syndrome were recovering from a viral infection, usually either influenza (flu) or chickenpox
  • Aspirin - many children who developed Reye's syndrome had previously taken aspirin to treat the symptoms of their viral illness

Due to the possible link between Reye's syndrome and aspirin, the medicines watchdog, Irish Medcines Board  recommends that children under 16 years old should not take aspirin unless advised by a doctor.

How common is Reye's syndrome?

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.

There was an average of 41 cases of Reye's syndrome a year in Ireland and the UK during the 1980s. The average number of cases a year fell to nine during the 1990s. In 2002, there was one confirmed case of Reye's syndrome. Up to April 2009 there have been three suspected cases.

Despite the decrease, some healthcare professionals believe that 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 equally, and it affects all races.


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

As a result of advances in diagnosing and treating Reye's syndrome, it is now estimated that 8 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. See Reye's syndrome - complications for more information.

Inherited metabolic disorders

It is now thought that many children who present at hospital with symptoms of Reye's syndrome actually have an inherited metabolic disorder, which is known as a ‘Reye-like’ illness.

An inherited metabolic disorder is a condition that 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. This can cause symptoms similar to those of Reyes syndrome, such as drowsiness.

In some cases, the build-up of a chemical can have a toxic (poisonous) effect. In other cases, you may have a shortage of a chemical that is vital for your normal body functions. It is therefore important that the correct diagnosis is made, as in some cases a specific treatment may be available. 

Possible inherited metabolic disorders that may cause a Reye-like illness include defects that affect:

  • lipids (fatty substances)
  • amino acids (molecules that make up protein)
  • carbohydrates (used as fuel for your body)

Page last reviewed: 13/07/2011

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

The 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. These symptoms can include:

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

When to seek medical advice

You should always contact your GP 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 GP.

Page last reviewed: 13/07/2011

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.

Genetic factors

It is possible that 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 the part of a human cell that is known as the mitochondria. 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 that are associated with Reye's syndrome, such as confusion and delirium.

Aspirin by another name

As well as not giving children under 16 aspirin, you should also not give them any products containing:

  • acetylsalicylic acid
  • acetylsalicylate
  • salicylic acid
  • salicylate
  • salicylate salts

Bonjela and Bonjela Cool Mint Gel both contain salicylate salts, which have the same effect on the body as aspirin. They should not be given to children under 16.

Page last reviewed: 13/07/2011

See your GP immediately, or visit the nearest accident and emergency (A&E) department, if you think that your child may have Reye's syndrome. If your child has taken aspirin, inform your GP or the healthcare professional who treats 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

Inherited metabolic disorders affect the chemical reactions that take place in the body. Some can cause symptoms that are similar to Reye's syndrome, so it is important to rule these out. Some inherited metabolic disorders can be treated to prevent the symptoms from returning.

If an inherited metabolic disorder is diagnosed, it may be necessary to check the child's brothers or sisters to see if they also have the condition. 


During the first stage of diagnosis, blood 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:

  • a computerised tomography (CT) scan
  • lumbar puncture
  • biopsy

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.

See the Health A-Z topic about CT scans for more information.

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 that the child may have brain swelling.

See the Health A-Z topic about Lumbar punctures for more information.


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

See the Health A-Z topic about Biopsies for more information.

Page last reviewed: 13/07/2011

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.

Possible medicines

Your child may be given medicines intravenously (directly into a vein). Possible medication that your child could be given include:

  • chemicals and fluids to correct the blood chemistry and supply nutrients - for example, 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
  • anti-emetic 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.

Page last reviewed: 13/07/2011

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:

  • have symptoms of depression or anxiety
  • be clingy or needy
  • have a fear of hospitals or healthcare professionals 
  • wet the bed

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 GP 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 that are associated with brain damage and 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 (dysphagia)
  • difficulty using the toilet
  • difficulty dressing

Living with a disability 

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

Page last reviewed: 13/07/2011

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

Other names for aspirin include:

  • acetylsalicylic acid
  • acetylsalicylate
  • salicylic acid
  • salicylate
  • salicylate salts - found in Bonjela (a treatment for mouth ulcers)

Alternatives to aspirin

If your child or teenager has flu (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:

  • asthma
  • kidney disease
  • liver disease

Check with your GP or pharmacist if you are unsure. You can also see the Health A-Z topics about Paracetamol and Ibuprofen for more information.

Conditions that need aspirin

Some children under 16 years old have specific conditions which 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 GP may decide that the benefit of taking medication that contains aspirin outweighs the risk. If your GP 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.

See the Health A-Z topics about Chickenpox vaccination and Flu vaccination for more information.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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