Reye’s syndrome is a rare but extremely serious condition that can affect children, particularly those between the ages of 6 and 12. It causes dangerous swelling in the brain and liver damage. It is most often linked to giving children aspirin during a viral illness such as the flu or chickenpox. Every Canadian parent and caregiver should know the warning signs — and understand why aspirin is not safe for children.
What Is Reye’s Syndrome?
Reye’s syndrome is a condition that damages the brain and liver at the same time. It is not an infection, and it is not contagious. However, it typically appears after a viral illness that is contagious, such as influenza or chickenpox.
The condition is considered a medical emergency. Without fast treatment, it can lead to coma or death. Fortunately, because Canadian health authorities and doctors have worked hard to warn parents about the aspirin risk, cases have become much less common in recent decades.
According to Health Canada, aspirin and products containing salicylates should not be given to anyone under 18 years old unless a doctor specifically approves it.
What Causes Reye’s Syndrome?
Doctors do not fully understand every cause of Reye’s syndrome. However, the strongest link is between aspirin use and viral infections in children. For example, giving a child aspirin to reduce fever during the flu or chickenpox greatly increases the risk.
The damage happens at the cellular level. Aspirin appears to injure tiny structures inside cells called mitochondria. These structures produce energy for the cell. When they are damaged — especially in liver cells — a chain reaction begins that destroys the cell itself. This leads to organ failure.
In addition, some researchers have looked at other possible triggers. These include acetaminophen use and even some mouthwashes that contain salicylate. However, the science on these links is still not definitive. Aspirin remains the clearest and most studied risk factor.
Is Reye’s Syndrome Contagious?
No. Reye’s syndrome itself cannot spread from person to person. The viral illness that triggers it — such as the flu — can spread. However, the syndrome is a reaction inside the child’s own body, not an infection that passes between people.
Recognising the Symptoms of Reye’s Syndrome
Symptoms of Reye’s syndrome usually appear 3 to 7 days after a child takes aspirin during a viral illness. The condition can move very quickly. In some cases, a child’s condition can deteriorate seriously in as little as 2 hours.
Parents and caregivers should watch for these early warning signs:
Sudden, repeated vomiting not explained by a stomach illness
Unusual tiredness or lack of energy
Loss of interest in play or normal activities
Irritability or personality changes
Confusion or difficulty speaking clearly
Drowsiness that worsens over time
As the brain swelling gets worse, more serious symptoms can develop. These include:
Disorientation — the child does not know where they are
Rapid, shallow breathing (hyperventilation)
Aggressive or combative behaviour
Seizures
Abnormal body posturing
Loss of consciousness or coma
These later symptoms are signs of a life-threatening emergency. Call 911 immediately if your child shows any of these signs. Do not wait to contact a walk-in clinic — go directly to your nearest emergency department.
How Is Reye’s Syndrome Diagnosed?
Diagnosing Reye’s syndrome can be challenging. Its symptoms look similar to many other conditions. Therefore, doctors must rule out other causes first. Even so, specialists always consider Reye’s syndrome when a child has altered mental status and severe, repeated vomiting.
According to the Mayo Clinic’s overview of Reye’s syndrome, doctors use several criteria to confirm the diagnosis:
Acute non-inflammatory brain dysfunction (encephalopathy) with deeply altered consciousness
Liver dysfunction, shown by elevated liver enzymes on blood tests
Changes in blood cell counts, including low lymphocytes
Evidence of brain swelling on imaging or examination
Jaundice — a yellowing of the skin — is not always present. However, when it does appear, it often signals a more serious outlook. Doctors may also use blood tests, urine tests, liver biopsies, and brain imaging to confirm the diagnosis and assess how far the damage has progressed.
Why Is Early Diagnosis So Important?
Time is critical with Reye’s syndrome. Treatment must begin within hours of the first symptoms. The longer the delay, the lower the child’s chances of a full recovery. Brain damage and liver failure can become permanent very quickly. This is why any suspected case requires immediate emergency care — not a call to a family doctor’s office the next morning.
Treatment for Reye’s Syndrome
There is no single cure for Reye’s syndrome. Instead, treatment focuses on limiting brain and liver damage and preventing complications. The main goal is to support the child’s body while it recovers.
Children with Reye’s syndrome are admitted to a paediatric intensive care unit (PICU). There, they are monitored 24 hours a day. Treatment typically includes:
Intravenous (IV) fluids to restore hydration and correct electrolyte imbalances
Glucose (sugar) given through an IV to prevent low blood sugar
Medications to reduce brain swelling and control pressure inside the skull
Monitoring of liver function and blood clotting
Breathing support if needed
Children who receive treatment early have much better outcomes. Many recover fully. However, in severe cases, there can be lasting neurological effects. This is why prevention — above all else — remains the most important strategy.
How to Prevent Reye’s Syndrome in Canada
The single most important step you can take is simple: never give aspirin to anyone under 18 unless a doctor has specifically told you it is safe. This includes all products that contain ASA (acetylsalicylic acid) or salicylates. Always read labels carefully before giving any medication to a child.
Fortunately, there are many safe and effective alternatives available at any Canadian pharmacy. Acetaminophen (such as Tylenol) and ibuprofen (such as Advil) are both approved for children when used correctly. These medications reduce fever and relieve pain without the risk of Reye’s syndrome.
In addition, keep the following prevention tips in mind:
Check the labels of all cold, flu, and pain relief medications for children — some contain hidden salicylates
Do not use adult medications on children without a doctor’s guidance
Ensure your child is up to date on flu and chickenpox vaccinations — preventing the viral illness also prevents the trigger
Ask your pharmacist if you are unsure whether a product is safe for your child
Canada’s intense public health campaigns around aspirin safety are a key reason why Reye’s syndrome is now rare. However, because it is rare, some doctors may not immediately think of it. Parents who know the signs can make a life-saving difference.
When to See a Doctor
If your child has recently had the flu, chickenpox, or another viral illness and took aspirin — even once — watch them closely over the following week. If you notice any of the early symptoms listed above, act quickly.
For mild concerns or general questions about safe fever treatment, your family doctor or a walk-in clinic can help. Many provinces also offer nurse advice lines — for example, Ontario’s Telehealth Ontario (1-866-797-0000) and BC’s 8-1-1 HealthLink. These services can guide you on next steps.
However, if your child is vomiting repeatedly, seems confused, unusually drowsy, or is having seizures, do not wait. Go directly to the nearest hospital emergency department or call 911. These symptoms require immediate evaluation by an emergency paediatrician. Reye’s syndrome can worsen within hours, and early treatment saves lives.
Always speak with a qualified healthcare provider before giving your child any new medication — including over-the-counter products. Your child’s health plan through your provincial health coverage can connect you with the right care at no cost for most services.
Frequently Asked Questions About Reye’s Syndrome
Can Reye’s syndrome be caused by children’s aspirin?
Yes. Even low-dose or “children’s” aspirin can trigger Reye’s syndrome when given during a viral illness. Health Canada advises that no child under 18 should take aspirin or ASA-containing products unless a doctor specifically approves it.
How quickly does Reye’s syndrome develop?
Reye’s syndrome typically begins 3 to 7 days after aspirin is given during a viral illness. However, once symptoms start, the condition can become life-threatening within just 2 hours. Early recognition and emergency treatment are essential.
What should I give my child instead of aspirin for fever?
Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) are safe and effective alternatives for reducing fever and pain in children. Always follow the dosage instructions on the label or ask your pharmacist or family doctor for guidance.
Is Reye’s syndrome fatal?
Reye’s syndrome can be fatal if it is not treated quickly. Without prompt medical care, it can lead to coma or death due to severe brain swelling and liver failure. With early treatment in a paediatric intensive care unit, many children recover fully.
How common is Reye’s syndrome in Canada today?
Reye’s syndrome is now very rare in Canada, largely due to public health campaigns warning parents not to give children aspirin. However, it still occurs, and awareness remains important. Because it is uncommon, it can sometimes be missed on a first medical visit.
Can adults get Reye’s syndrome?
Reye’s syndrome is most common in children between the ages of 6 and 12, but it can affect teenagers and, in rare cases, adults. Many experts recommend avoiding aspirin in anyone under 20 years of age unless directed by a doctor.
Key Takeaways
Reye’s syndrome is a rare but life-threatening condition affecting the brain and liver, most common in children aged 6 to 12.
It is strongly linked to giving children aspirin (ASA) during viral illnesses such as the flu or chickenpox.
Never give aspirin to anyone under 18 without a doctor’s explicit approval — this is the single most effective prevention step.
Safe alternatives include acetaminophen and ibuprofen, available at any Canadian pharmacy.
Early symptoms include sudden vomiting, unusual tiredness, confusion, and personality changes — these require urgent attention.
If your child shows signs of confusion, seizures, or loss of consciousness, call 911 or go to the nearest emergency department immediately.
Treatment in a paediatric intensive care unit, started early, gives children the best chance of a full recovery.
For more information, visit the Healthline guide to Reye’s syndrome or speak with your family doctor.
This article is for informational purposes only and does not replace professional medical advice. Always consult your family doctor, a walk-in clinic, or call your provincial health line if you have concerns about your child’s health.
