The cause of Reye's syndrome is unknown. Some studies suggest a link with the use of the medicine, aspirin. Aspirin should only be given to children under 16 on the advice of a doctor. We explain more as well as how common it is.


The cause is unknown; but a number of studies suggest a link between the development of Reye’s syndrome and the use of aspirin to treat the viral infection which precedes it.

These studies did not prove that aspirin is the only cause of Reye’s syndrome but showed that it can precipitate it in the presence of other factors such as a viral infection and possibly some innate susceptibility.

Other chemical substances including insecticides and emulsifiers have also been implicated but the evidence that these are involved is controversial. Risk factors for adult Reye’s syndrome have not been comprehensively studied.

Preventing Reye’s syndrome

Aspirin should only be given to children under 16 on the advice of a doctor. 

Children under 16 years should also not take any products containing:

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

Because there are alternatives, there is no need to use aspirin for feverish illnesses in childhood. Since 1986, aspirin preparations have been labelled with differing warnings. The latest advice from the Medicines and Healthcare products Regulatory Agency (MHRA) which came into force on 1 October 2003, requires all aspirin products to carry a warning that children under 16 should not take aspirin unless on the advice of a doctor.

The warning that appears on the Carton/Label and Patient Information Leaflet is as follows.

Carton/Label: Aspirin Products
Do not give to children aged under 16 years, unless on the advice of a doctor.
Patient Information Leaflet: Aspirin Products
There is a possible association between aspirin and Reye’s Syndrome when given to children. Reye’s syndrome is a very rare disease which can be fatal. For this reason, Aspirin should not be given to children aged under 16 years, unless on the advice of the doctor.

On 23 April 2009 the MHRA issued precautionary advice for topical oral pain relief gels containing salicylate salts. The main products affected are Bonjela and Bonjela Cool Mint Gel. This is due to salicylate salts having the same affect on the body as aspirin. The new advice recommends these products are not used in those under 16 years of age. This is a precautionary measure only and there are no new safety concerns.

Carton/Label, Tube, Patient Information Leaflet: Topical Oral Pain Relief Gels
Do not give to children and adolescents under 16 years of age this is because there is a possible association/link* between salicylates and Reye’s syndrome when given to children. Reye’s syndrome is a very rare disease which affects the brain and liver and can be fatal.

Because aspirin is readily available in supermarkets and pharmacies throughout the United Kingdom, ‘aspirin’ often makes headline news about the positive effects its use can have for adults. As a consequence when it comes to their children, parents become complacent, and do not notice or ignore the warning about the potentially devastating effect the drug can have upon children and young people if given for a viral infection. It is important that all parents heed this warning.

Is Reye’s syndrome a common condition?

Reye’s syndrome was first described in 1963 by an Australian pathologist, R. Douglas Reye, MD – see a short biography and photograph in About us.

Since then it has been recognised in many parts of the world. It used to occur in minor epidemics, which in some countries (most notably the USA) were associated with influenza epidemics.

Although the exact incidence of the condition in the UK and Ireland is not known, reported cases have fallen dramatically from nearly a hundred in 1984 to only one in 2002. Since then no active surveillance of the disorder has been undertaken.

In the period 2003-2009 three cases of Reye’s syndrome or Reye-like disorders in England and Wales have been ascertained by the adverse drug reaction surveillance scheme of the Medicines and Healthcare products Regulatory Agency (MHRA). In one of these a 14-year-old girl had been given oral aspirin for a viral illness – she also turned out to have one of the Reye-like inherited metabolic disorders; the second was an infant who had been given an excessive amount of an oral teething gel containing choline salicylate; the third patient had not been exposed to any form of aspirin or salicylate, the illness was thought to be related to an antiretroviral drug.

It is likely that there is some under-reporting and under-diagnosis, but this downward trend has also been seen in the USA and is attributed to reduction in the use of aspirin in children since the public warnings in 1986. Nevertheless there may be a resurgence, especially if there is a large ‘flu’ epidemic or the aspirin warning is ignored or forgotten as the time goes by. It is thus essential that clinicians retain high diagnostic awareness of Reye’s syndrome and Reye-like disorders.

For further information on surveillance of Reye’s syndrome see BPSU’s past studies.

Date of next review: December 2021

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