FDA Ponders Psychiatric Warning for Common Flu Drugs

An FDA staff report recommends adding label warnings about possible neuropsychiatric side effects in individuals taking the influenza drugs oseltamivir (Tamiflu) and zanamivir (Relenza).

The report was prepared for a meeting of the Pediatric Advisory Committee to take place this week. The FDA found 596 cases of neuropsychiatric events associated with oseltamivir and 115 with zanamivir. The cases, mostly in people age 21 or younger and mostly from Japan, included delirium, hallucinations, and impulsive behavior, including a desire to jump. Five fatalities were associated with oseltamivir use while none were associated with zanamvir.

The agency cautioned it could not rule out the possibility that the behavior was due to the illness rather than the treatment. However, the reports "raise the question" of whether the events result from the neuraminidase inhibitor class. It said "it seems prudent" for both drugs to carry label warnings of hallucinations, delirium, and abnormal behavior.

Glaxo and Roche, which make the two drugs, said label updates are unnecessary, because the events could have resulted from flu symptoms.