What Is Reye’s Syndrome, and How Is It Related to Aspirin?

Have you ever heard you shouldn’t give aspirin to kids? Well, that’s because aspirin can cause Reye’s syndrome, a rare but life-threatening condition that causes brain swelling and liver damage. And it can potentially lead to irreversible brain damage or death. 

It usually happens in kids younger than 18 years, and it mostly affects those ages 4 to 12 years. In rare cases it affects infants or young adults (ages 18 to 20).

This probably all sounds pretty scary. But with early treatment, children of any age with Reye’s syndrome can fully recover. And it’s also preventable in many cases. We’ll go through what every parent and caretaker needs to know to keep their children safe.

What is Reye’s syndrome?

Reye’s syndrome is a rare condition that affects kids more than adults. It’s characterized by two main features:

• Inflammation and swelling in the brain

• Liver dysfunction

Experts have observed that it usually starts after a child is recovering from a viral illness. Once it starts, Reye’s syndrome progresses quickly and can be life-threatening. It can start to affect other parts of the body — like the heart and kidneys. But the main problem is the swelling in the brain. 

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Experts are still trying to understand exactly why and how it happens. But they have identified a few different factors that seem to be a common thread in kids who develop Reye’s syndrome. 

What causes Reye’s syndrome?

In most cases, Reye’s syndrome happens after a child takes aspirin to help them feel better during or after a viral illness — most often the flu or chickenpox. But what’s the link between aspirin, a viral infection, and Reye’s syndrome? 

Scientists believe that it’s related to the mitochondria in the liver. Mitochondria are like the engine in a cell. They are the parts of a cell that produce energy. And they can usually keep up with a few stressful events at one time. But if there are too many stressors, they can get overwhelmed. 

In Reye’s syndrome, liver mitochondrial stress comes from viruses like the flu and chickenpox alone — or from taking aspirin during or after these types of infections. And when the mitochondria can’t support liver function, the liver can’t keep up with cleaning out the toxins in the blood. These toxins, like ammonia, build up in the blood and cause the brain to swell. 

How does aspirin cause Reye’s syndrome?

It isn’t exactly clear why aspirin causes Reye’s syndrome when other medications don’t present that risk. But given this risk, it isn’t safe to give aspirin to anyone under the age of 19. 

The FDA recommends that you should never give aspirin to a child for viral infections — whether they have a fever. And it’s important to know that plenty of oral medications contain the same active ingredient as aspirin (salicylate). 

Here are some other forms of that active ingredient to look for and avoid: 

• Aminosalicylates 

• Acetylsalicylic acid

• Acetylsalicylate

• Salicylic acid

• Salicylate salts 

How much aspirin will cause Reye’s syndrome in a child?

There’s no safe dose of aspirin for kids when it comes to preventing Reye’s syndrome. In other words, even normal or low doses of aspirin can cause it. But the risk seems to increase with higher doses. 

Symptoms of Reye’s syndrome

Symptoms of Reye’s syndrome can start and progress quickly. They typically start between 12 hours and 3 weeks after recovery from a viral illness. 

The first symptoms are usually:

• Repeated vomiting

• Lethargy

• Confusion

After this, the illness can progress quickly. And in the later stages, symptoms can include:

• Agitation and delirium

• Dilated pupils

• Rigidity or abnormal reflexes

• Rapid breathing

• Rapid heart rate

• Seizures

• Coma

But early treatment can usually stop it from progressing. 

Treatment for Reye’s syndrome

The treatment for Reye’s syndrome is supportive. This means that there’s no direct treatment that reverses the condition. Instead, the treatment is aimed at minimizing the symptoms and complications. 

Since Reye’s syndrome is a very dangerous condition, a child who has it will need immediate hospitalization. And they will usually require support at the level of an intensive care unit (ICU). A child might be hooked up to a number of different monitors that measure the pressure inside the skull, body temperature, and oxygen levels — among other important body functions.

The stage of Reye’s syndrome helps to determine the specific treatment, which may include: 

• IV (intravenous) hydration with glucose and electrolytes: IV hydration with glucose and electrolytes helps to balance electrolytes and keep fluid in the blood vessels instead of the brain, where it can cause swelling. 

• Medications: Healthcare providers will use medications to help reduce swelling in the brain and to prevent or treat seizures. 

• Breathing machine: If a child is in a coma and can’t breathe on their own, they will need help to breathe with a breathing machine (ventilator).

Long-term complications of Reye’s syndrome

About two-thirds of children who survive Reye’s syndrome have a full recovery. And the earlier a child is diagnosed, the better the chance for recovery. 

But even if a child receives treatment for Reye’s syndrome, there’s a chance that they may have some long-lasting issues afterward. When the brain is swollen for a long time, it can cause permanent brain damage. Depending on what part of the brain is damaged, the long-term complications can vary dramatically — from a mild learning disability or behavior problems to severe disability in thinking, communication, or movement. 

How to prevent Reye’s syndrome

Although it’s rare, Reye’s syndrome is extremely dangerous. And you can prevent it by not giving aspirin or aspirin-related medications to anyone younger than 19 years — unless a healthcare provider recommends it. For example, aspirin is part of the treatment for certain conditions like Kawasaki disease, a condition in young children where the immune system attacks blood vessels. 

If you think your child needs an over-the-counter (OTC) medication for pain or fevers,  Motrin, Tylenol, or Advil are options that don’t contain aspirin. You should follow the instructions on the label of these medications, since dosing is different for children. And remember, don’t give ibuprofen (Motrin and Advil) to a child younger than 6 months.

You can also help prevent viral illnesses in your children that can lead to Reye’s syndrome. By keeping your children on schedule with their vaccinations, the chance of their getting influenza and chickenpox decreases.

When to see a doctor for concerns of Reye’s syndrome

Since Reye’s syndrome can be fatal or cause long-term complications, seek medical attention right away if you think your child may have it. This is especially the case if your child has recently had the flu or chickenpox — or if they have taken aspirin or another aspirin-containing medication like Alka-Seltzer (sodium bicarbonate).

As mentioned above, the first symptom is usually vomiting and a change in their mental state. This could look like lethargy, confusion, or even abnormal nightmares. 

Even if they haven’t taken any aspirin, call 911 for immediate assistance if you notice any of the following symptoms in your child:

• Uncontrollable vomiting

• Loss of consciousness (passing out)

• Convulsions or seizure

• Hallucinations (seeing, hearing, or feeling things that aren’t there)

• Rapid breathing

• Lethargy (extreme tiredness)

Why trust our experts?

Written by:

Lauren Geoffrion, MD

Lauren Geoffrion, MD, is a current medical writer at GoodRx and MedicineX. She has written several articles on Psychiatry & Psychotherapy, a website that publishes CME-accredited podcasts and accompanying articles on mental health. She has also contributed to articles in the Investigative Journal of Medicine.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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