Health Canada has ordered changes to the labelling of Tamiflu to mention reports that some Japanese teenagers taking the medicine tried to commit suicide.
Tamiflu, the brand name for oseltamivir, is an effective treatment for influenza and is also considered one of the best defences against bird flu.
Japanese government authorities recently revealed that a number of young people had been injured after taking the drug. Fifteen people aged 10 to 19 have jumped from buildings, while another jumped in front of a truck and was killed. Five young people have died in such incidents since 2004.
Japan has now restricted use of Tamiflu in patients 10 to 19 years old.
Health Canada says it is expecting further information from Tamiflu's manufacturer, Hoffman-LaRoche Ltd. Until then, it is changing the drug's labelling.
"The Canadian labelling for Tamiflu has recently been updated to include new safety information resulting from adverse reaction reports of abnormal or suicidal behavior in Japanese children or teenagers taking Tamiflu," Health Canada said.
Health Canada says that as of Feb. 28, there were no reports that Canadian teenagers taking the drug had shown signs of abnormal behavior.
It says no clear connection has been made between the Japanese cases and Tamiflu and notes that the symptoms of influenza -- high fever or other complications -- can affect mental state, which in turn can lead to abnormal behaviour.
Roche says studies from Japan and the United States showed there was no established causal link between psychiatric problems and Tamiflu.
If taken within 48 hours of the onset of flu symptoms, Tamiflu reduces the length of the sickness by one day, on average. It can also be used to prevent infection during flu outbreaks.
Consumers who want more information can contact Health Canada's public inquiries line toll free at 1-866-225-0709.
