Flu drug once blamed for seizures in kids gets a surprising reversal

New research from Monroe Carell Jr. Children's Hospital at Vanderbilt now challenges that long-held concern about oseltamivir, widely known as Tamiflu.

Study Finds Lower Risk With Oseltamivir Use

The study, published in JAMA Neurology, found that children who received oseltamivir during a flu illness were less likely to experience serious neuropsychiatric events. These included conditions such as seizures, altered mental status, and hallucination.

"Our findings demonstrated what many pediatricians have long suspected, that the flu, not the flu treatment, is associated with neuropsychiatric events," said principal investigator James Antoon, MD, PhD, MPH, assistant professor of Pediatrics in the Division of Pediatric Hospital Medicine at Monroe Carell. "In fact, oseltamivir treatment seems to prevent neuropsychiatric events rather than cause them."

What the Researchers Discovered

The study identified three key findings that together point to influenza as the main driver of these complications.

Influenza infection itself was linked to a higher rate of neuropsychiatric events when compared with children who did not have the flu, regardless of whether oseltamivir was used. Among children who did have influenza, those treated with oseltamivir experienced roughly a 50% reduction in neuropsychiatric events. Children without influenza who received oseltamivir as a preventive measure showed the same rate of events as children with no flu exposure.

"Taken together, these three findings do not support the theory that oseltamivir increases the risk of neuropsychiatric events," said Antoon. "It's the influenza."

Large-Scale Analysis of Pediatric Health Data

Researchers examined de-identified health records from children and adolescents ages 5-17 who were enrolled in Tennessee Medicaid between July 1, 2016, and June 30, 2020.

The study followed 692,295 children over four years, with a median age of 11. During that time, 1,230 serious neuropsychiatric events were recorded, including 898 neurologic events and 332 psychiatric events.

The clinical outcomes included neurologic conditions such as seizures, encephalitis, altered mental status, ataxia/movement disorders, vision changes, dizziness, headache, and sleeping disorders. Psychiatric outcomes included suicidal or self-harm behaviors, mood disorders, and psychosis/hallucination.

Why the Findings Matter for Families

"The 2024-2025 influenza season highlighted the severity of influenza-associated neurologic complications, with many centers reporting increased frequency and severity of neurologic events during the most recent season," said Antoon. "It is important for patients and families to know the true risk-benefit profile of flu treatments, such as oseltamivir, that are recommended by the American Academy of Pediatrics."

Senior author Carlos Grijalva, MD, MPH, professor of Health Policy and Biomedical Informatics at Vanderbilt University Medical Center, emphasized that early treatment remains critical.

"These flu treatments are safe and effective, especially when used early in the course of clinical disease," he said.

Reassurance on Flu Treatment Safety

The research team hopes the findings will help reassure caregivers and healthcare providers about the safety of oseltamivir and its role in reducing flu-related complications in children.

The study was funded by the National Institutes of Health (grants K23AI168496, K24AI148459 and P50HD106446).