What Is Reye's Syndrome?

Medically Reviewed by Amita Shroff, MD on December 16, 2022
3 min read

Reye’s syndrome is a rare but serious disease that causes swelling in the liver and brain. It can affect people of any age, but it is most often seen in children and teenagers recovering from a virus such as the flu or chickenpox.

Studies have found that the main risk factor for Reye’s syndrome is taking aspirin or other related drugs, called salicylates.

Because of this, doctors recommend that children and teenagers recovering from viral infections should avoid taking aspirin.

Doctors don’t fully understand what causes Reye’s syndrome. They do know that some people are prone to get it when they take aspirin for a virus.

Others have a greater chance of getting it if they:

  • Have a disorder that affects how their bodies break down fatty acids
  • Have been exposed to certain toxins, including paint thinners and products to kill insects and weeds

When Reye’s syndrome strikes, cells throughout your body become swollen and build up fats. In turn, your blood sugar levels drop. Ammonia and acid levels in the blood rise. These changes can hit many organs, such as the brain and liver, where severe swelling can occur.

The signs of Reye’s typically appear 3 to 5 days after the start of a viral infection.

In children younger than age 2, early symptoms may include diarrhea and rapid breathing. In older children and teenagers, early symptoms may include ongoing vomiting and unusual sleepiness

As the syndrome goes on, symptoms can become more severe, and may include:

  • Personality changes (more irritable or aggressive)
  • Confusion or hallucinations
  • Weakness or inability to move arms or legs
  • Seizure or convulsions
  • Extreme tiredness
  • Loss of consciousness

Reye’s can be life-threatening. You should call 911 if you see these severe symptoms. Early diagnosis and treatment is crucial.

The syndrome can be mistaken for other conditions, including meningitis (a swelling of membranes covering the brain and spinal cord), a diabetes reaction, or poisoning.

Doctors don’t have a specific test for Reye’s. They usually do urine and blood tests. They also screen for disorders involving fatty acids.

Other tests may include:

  • Spinal taps (a needle is inserted into a space below the end of the spinal cord to collect fluid)
  • Liver biopsies (a needle is pushed through the abdomen into the liver to get a sample of tissue)
  • Skin biopsies (a doctor scrapes a small skin sample to test)
  • CT or MRI scans (which can also rule out other problems)

There’s no single treatment that will stop Reye’s syndrome, but doctors can do some things to make sure it is managed. They can also try to prevent more severe symptoms and see that brain swelling is held down. These steps include:


  • Intravenous (IV) fluids
  • Diuretics to help your body get rid of salt and water (and stop swelling)
  • Medications to prevent bleeding
  • Vitamin K, plasma, and platelets (tiny blood cells that help form clots) in instances of liver bleeding

As doctors have gotten better at diagnosing Reye’s syndrome quickly and early, the death rate has dropped from around 50% to less than 20%. This means most children and teenagers who get the syndrome survive and recover completely.

How well a person recovers from Reye’s syndrome -- and the chances for long-term brain damage – depend a lot on how much the brain swells.

Cases that quickly get worse and lead to coma are more likely to lead to more brain damage.