Reye's Syndrome: Symptoms Worth Looking Out For

7. Hyperventilation or Irregular Breathing

As brain inflammation intensifies, the body’s automatic functions—like breathing—can become disrupted. Some children may begin hyperventilating or exhibit rapid, shallow breaths. Others may breathe irregularly, with long pauses or sudden gasps. These shifts are the body’s attempt to compensate for rising intracranial pressure and changes in blood pH caused by liver dysfunction. Parents should act fast if they notice abnormal breathing, particularly when combined with confusion, vomiting, or lethargy. Since Reye’s syndrome can progress rapidly, these changes in respiration may be one of the last signs before a medical emergency. Immediate evaluation in an emergency room is critical.

8. Enlarged Pupils or Uneven Pupil Size

Neurological changes caused by Reye’s syndrome can sometimes be seen in the eyes. Pupils may become enlarged and react slowly—or not at all—to light. In some cases, pupils may be uneven in size (anisocoria), which suggests pressure on specific areas of the brain. These signs indicate elevated intracranial pressure and are often seen in advanced stages of the syndrome. They should be treated as an emergency. If a child recovering from a viral illness begins showing unusual eye changes or unresponsiveness to light, it's time to seek urgent medical help. The eyes can tell you what words can’t.