Tamiflu to Carry Warning on Psychiatric Side-Effects

Tamiflu (oseltamivir phosphate) is to carry a warning on the label in the United States, following the reports of delirium, self-harm, hallucinations, and suicidal thoughts in Tamiflu users in Japan.

Between August 2005 and July 2006, there were 103 cases--95 of them in Japan--of psychiatric side-effects, of which 68 involved children under 17. On average, approximately 1 in 100,000 patients experienced psychologic disorders. It is still not clear whether the side-effects are due to the drug, the illness it is supposed to treat (flu), or both. A previous review by the U.S. Food and Drug Administration (FDA) staff covering 1999 to August 2005 found 126 cases of neuropsychiatric adverse events from people who took Tamiflu.

The FDA updated the drug's U.S. label and advised parents to watch out for such reactions in their children when being treated with the antiflu drug. While the relationship between the altered behavior and the drug was not known, the label had been amended to mitigate potential risk. The warning already exists in Japan.

Tamiflu is a product of Roche (Basel, Switzerland). The company released a statement saying it will work with regulators to make sure the medication's labeling is accurate.

"There is no evidence of a causal relationship between the use of oseltamivir and a likelihood of neuropsychiatric events in influenza patients,” said Roche spokesman Terence Hurley. "Tamiflu has demonstrated in clinical trials to be a safe and effective medication for influenza prevention and treatment.”

Tamiflu was approved by the FDA in 1999 and has been used by more than 42 million people in over 80 countries. Several governments have been increasing their stocks of Tamiflu, as part of a worldwide drive to shore up defenses against a possible spread of avian (H5N1 strain) bird flu infection among humans. The United States has a stock of 16 million doses, and expects to eventually have 50 million.



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