Reye's syndrome

Reye's syndrome is a very rare condition in which a child who has just been through a viral illness develops swelling of the brain while the liver stops doing its job. It unfolds over a matter of hours and is life-threatening without prompt care. This page has one unusual feature: almost everything on it comes down to a single practical rule. Reye's syndrome became rare not because doctors learned to treat it — there is no specific treatment and there never was — but because children stopped being given aspirin. So what follows is first of all about aspirin and about where it hides, and only then about the warning signs and the hospital.

How aspirin fits into this

There was a time when this syndrome counted as a familiar childhood illness: hundreds of cases a year, and one child in three did not survive. In the late 1970s and early 1980s several studies pointed the same way — almost every child who fell ill had been given aspirin or another salicylate shortly beforehand, for flu, for chickenpox or for an ordinary cold. Aspirin was withdrawn from use in children, and the illness all but vanished. A whole country now records a handful of cases a year, and many record none at all for years at a stretch.

The exact mechanism has never been fully pinned down. The salicylate is thought to damage mitochondria, the parts of the cell that generate energy, and they seem to be at their most vulnerable when the body is already busy with a virus. The liver stops clearing ammonia, it builds up in the blood, and the brain swells.

It is worth being clear about where the risk actually lies. It is not that aspirin is harmful in itself — adults are prescribed it constantly and for good reason. The risk is in the combination: a child, a viral infection and a salicylate. Far from every child given aspirin becomes ill, or the syndrome would not be a rarity, but there is no way of knowing in advance who will turn out to be vulnerable. Hence the rule adopted worldwide: children and teenagers are not given aspirin. Not "when the temperature is high", not "when it's flu" — not at all, with no qualifications about the illness.

There is exactly one exception: in certain conditions a doctor prescribes aspirin to a child deliberately, for instance in Kawasaki disease and in some heart conditions. That decision is made and monitored by the doctor, who knows the risk and follows the child up. It never becomes a decision made at home.

Where aspirin hides under other names

Parents who know the rule perfectly well still hand their child a salicylate now and then, simply without realising it. The word "aspirin" may not appear on the packet at all.

• Acetylsalicylic acid is aspirin. Same substance, different name.
• Combination sachets and effervescent tablets "for colds and flu". They blend several active ingredients, and a salicylate is easy to miss in the mix. Brand names differ from country to country, and the name tells you nothing about the contents.
• Products "for fever" and "for pain" sold under trade names in which the word aspirin never appears.
• Mouth gels, for ulcers and for teething: some are based on choline salicylate.
• Rubs and ointments for muscle and joint pain containing methyl salicylate, which is absorbed through the skin.
• Upset-stomach remedies based on bismuth subsalicylate.

Which gives a simple everyday rule: before giving a child any medicine, read the ingredients — the small print on the box or the leaflet inside, not the large name on the front. Look for "salicylate", "salicylic", "acetylsalicylic". If you are unsure, ask a pharmacist; it takes a minute. And never break an adult medicine in half to make a "child's dose": children's preparations have a different composition, not simply less of the same thing.

What to bring a temperature down with instead

The substitutes are the familiar ones: paracetamol and ibuprofen in children's formulations. The dose is worked out by the child's weight rather than guessed from their age; it is printed in the leaflet, and a doctor or pharmacist will confirm it.

Two things trip people up most often. First: if a child has already had a cold sachet, do not add paracetamol separately — the sachet almost certainly contains it, and the two together add up to an overdose. Second: during chickenpox paracetamol is usually preferred to ibuprofen, because ibuprofen is associated with more frequent skin infections in scratched blisters.

And a general point: the temperature itself is not the enemy. What matters is how the child looks and behaves, not the figure on the thermometer. You give something for a fever when the fever is making the child miserable, not to make the reading come out normal.

How it starts

The sequence in Reye's syndrome is quite recognisable, and it is worth remembering as a sequence rather than as a list of symptoms.

The child has had chickenpox, flu or another viral illness and is already on the mend — anything from a few days to a couple of weeks have passed, the fever has gone, they have perked up. And then:

• persistent vomiting begins. It comes back again and again, has nothing to do with meals and brings no relief;
• within hours, drowsiness and lack of energy follow: the child is hard to rouse and lies down all the time;
• then confusion: answers that make no sense, not recognising familiar faces, not knowing where they are;
• behaviour changes: irritability, aggression, crying for no reason or, the other way round, an odd blankness. Families usually put it as "he isn't himself";
• later come rapid breathing, seizures and loss of consciousness.

The key is not the vomiting on its own. Being sick after a viral illness is thoroughly ordinary in childhood and almost never means anything. What counts is the pairing: persistent vomiting plus a change in consciousness or behaviour in a child who had been getting better. That pair should not happen.

It affects school-age children most often, roughly between five and fourteen. In the very young the picture can differ: diarrhoea and fast breathing instead of vomiting, with drowsiness much harder to spot.

When to call an ambulance

If a child who has recently had a viral illness starts vomiting repeatedly, that alone is reason to have them seen by a doctor the same day rather than leaving it until morning.

Call an ambulance straight away (in Europe, the single number 112) if any of the following appears:

• a fit or seizure;
• you cannot wake the child, or they are not responding as they normally do;
• confusion or delirium, not recognising their parents;
• unusual floppiness: the body goes limp, the head falls to one side or backwards, the eyes will not focus on your face;
• fast, irregular or laboured breathing;
• loss of consciousness.

Make sure the doctor is told two things: that the child has recently had a viral illness, and which one, and what medicines they have been given — syrups, sachets, gels and anything handed over "just for the temperature". Best of all, bring the packets. A doctor works it out faster from the ingredients than from brand names recalled on the spot.

What happens in hospital

A child suspected of this is admitted immediately, to a hospital with paediatric intensive care. The diagnosis is put together from the whole picture: how the illness has unfolded, what the blood shows and what the scans show.

Blood and urine tests are done, with liver values, ammonia, glucose and clotting checked. A CT scan of the head and an electroencephalogram are usually arranged. Sometimes a lumbar puncture is needed to rule out meningitis, which starts in a similar way. The metabolism is looked at separately, as described below.

There is no treatment aimed at the syndrome itself: no antidote, no drug that halts it. What is done is to support the body until the swelling settles on its own — fluids and glucose through a drip, measures to bring the pressure inside the skull down and, if needed, help with breathing and monitoring in intensive care.

The outlook depends heavily on how early things start. With prompt treatment most children recover fully. The later it begins, the greater the chance of lasting neurological problems: difficulties with speech, memory, attention or movement. That is why every section above comes back to not waiting.

When aspirin has nothing to do with it

There is a small group of children in whom exactly the same picture develops with no aspirin anywhere in the story. The cause is an inherited metabolic disorder: most often a defect in breaking down fats, of which the best known is medium-chain acyl-CoA dehydrogenase deficiency (MCADD), and less often a urea cycle disorder. In these children the body cannot switch to its reserve fuel when vomiting stops food being absorbed, and a run-of-the-mill infection produces something indistinguishable from Reye's syndrome.

It is worth suspecting if the child is very young, if a similar episode has happened before, or if the family has had a case of sudden severe illness in a child during an unremarkable virus. That is why the metabolism is checked in every case.

For a family the distinction is decisive. If an inherited cause is confirmed, everything afterwards changes: long gaps without food are no longer safe, any illness with vomiting calls for a plan agreed with the doctor in advance, and relatives are tested too. Many countries look for these disorders in newborn screening, but the list of conditions included varies from country to country; a paediatrician can tell you what is on yours.

Online consultation

A remote appointment is ideal for exactly the thing that is best settled before any illness starts: going through the medicine cupboard at home and working out what your child can and cannot have. Send a photograph of the ingredients on the packet and the doctor will tell you whether there is a salicylate in it and what to use instead. The same unhurried conversation covers what to give your particular child for a fever, taking their weight and their other medicines into account, and what to do during chickenpox.

The second common question is vomiting after an infection. The doctor will go through how the child is behaving, whether they are drinking, whether they recognise you, and will say whether this is the ordinary version or whether they need to be seen in person the same day. The emergency signs listed above are not assessed remotely: with those you call an ambulance.

This material is for information only and does not replace medical advice.