Reye's syndrome: symptoms, causes and prevention

The NHS calls Reye's syndrome a very rare condition that can affect children or young adults after an illness like flu or chickenpox, and warns that it can cause serious brain problems if not treated quickly. The National Reye's Syndrome Foundation, whose site is hosted by the Royal College of Paediatrics and Child Health, says unless it is diagnosed and treated successfully, death or severe disability may result.

It affects the brain and liver. The NHS says it is not clear exactly why it happens, and the same foundation notes the cause is unknown.

The NHS says symptoms often start 1 to 3 weeks after the child recovers from a virus. A child may keep vomiting, be drowsy and lack energy, feel confused, change in behaviour such as becoming irritable or aggressive, breathe quickly with a fast heart rate, have fits or lose consciousness.

The NHS draws a clear line between emergencies and urgent concerns. Call 999 or go to A&E if your child has a fit, finds it difficult to breathe, is confused, is limp, floppy or not responding as normal, or loses consciousness. Ask for an urgent GP appointment or get help from NHS 111 if your child keeps vomiting, is drowsy or lacks energy, or is not their normal self. Tell the clinician about any recent infection and whether the child has taken aspirin.

• Persistent vomiting after a recent viral illness.

• Unusual drowsiness, confusion or behaviour change.

• Fast breathing or a fast heart rate.

• A fit, floppiness or loss of consciousness: call 999.

The exact cause is unknown. The NHS says it has been linked to salicylate medicines, particularly aspirin, in children and young people under 16. The National Reye's Syndrome Foundation explains that studies suggest a link between aspirin used to treat the viral illness and the development of Reye's syndrome. The studies did not prove aspirin is the only cause, but showed it can precipitate the condition alongside a viral infection and possibly some inherent susceptibility.

The NHS adds that sometimes a child with a rare genetic condition, such as medium-chain acyl-CoA dehydrogenase deficiency (MCADD), can get Reye's syndrome, which has nothing to do with aspirin. The foundation describes a wider group of inherited metabolic disorders, 26 identified in its list, that can mimic the illness. They are often called Reye-like syndromes, and doctors should look for them before accepting a diagnosis of classic Reye's syndrome.

The NHS advice is direct. Do not give aspirin to children under 16 unless their doctor prescribes it, and do not give children under 16 any medicine containing salicylic acid or salicylate, which includes some mouth ulcer gels. Ask a pharmacist for alternatives suitable for children. The NHS aspirin page repeats that aspirin should not be given to people aged 15 or under because it can cause Reye's syndrome in rare cases.

The foundation says all aspirin products in the UK must carry a warning that children under 16 should not take aspirin unless advised by a doctor. It also points to the MHRA's precautionary advice that topical oral pain relief gels containing salicylate salts should not be used in under-16s. Because there are alternatives, it says there is no need to use aspirin for feverish illnesses in childhood.

The NHS also suggests thinking about vaccinating children against flu and other common viruses, which reduces the infections that can come before Reye's syndrome.

If a child might have Reye's syndrome the NHS says they will be referred to a specialist for tests. These may include blood and urine tests, a CT scan, an electroencephalogram (EEG), a lumbar puncture to take a sample of spinal fluid, and a liver biopsy.

The foundation says there is no single laboratory test for classic Reye's syndrome, and that the diagnosis should be given only when other causes, the Reye-like inherited metabolic disorders, have been excluded. In the UK it notes that an initial diagnosis of Reye's syndrome has sometimes been revised to an inherited metabolic disorder, which matters because those conditions may need special drugs or diets and affect other family members.

The NHS says a child with Reye's syndrome needs to go into hospital straight away. Treatment may include help with breathing, fluids given into a vein to prevent dehydration, and medicines to treat and manage symptoms. The foundation notes that if the diagnosis is made, the child needs to be admitted to intensive care and that a child's life may depend on emergency treatment in the nearest children's unit.

The NHS says most children make a full recovery if treated quickly, but some have long-term brain problems. The foundation offers advice to parents of children who have survived, to help them understand the child's needs and secure services such as educational and therapy support.

Reye's syndrome is now extremely uncommon in the UK. The foundation says reported cases fell dramatically from nearly a hundred in 1984 to one in 2002, and attributes the fall to reduced use of aspirin in children after public warnings in 1986. It cautions that there could be a resurgence if warnings are forgotten or ignored, particularly in a large flu season.

For most families the practical message is calm and simple. Treat a child's fever or pain with a medicine suited to children, read the label, and ask a pharmacist when unsure. Seek help promptly if a child who has had flu or chickenpox starts being repeatedly sick and unusually sleepy.