The new warning notes reports of self-injury and delirium in flu patients taking Tamiflu, mainly among children in Japan.
The FDA knows of 103 reported cases -- 95 from Japan, five from the U.S., and three from other countries. Sixty of the 103 cases featured delirium with prominent behavioral disturbance such as panic attack, hallucinations, and convulsions; only one of those cases occurred in the U.S.
It's not known if Tamiflu caused any of those events.
"People with the flu, particularly children, may be at an increased risk of self-injury and confusion shortly after taking Tamiflu and should be closely monitored for signs of unusual behavior," states Tamiflu's new warning.
"Patients with influenza a should be closely monitored for signs of abnormal behavior throughout the treatment period," the warning also notes.
"A healthcare professional should be contacted immediately if the patient taking Tamiflu shows any signs of unusual behavior," states the warning.
The drug company Roche, which makes Tamiflu, sent a letter dated Nov. 13 to health care workers about the new warning. Roche is a WebMD sponsor.
In a Roche news release, the drug company states that "while any relative contribution of Tamiflu to these events is unknown, Roche is committed to working closely with the FDA to ensure that the product label accurately reflects the reports, so that healthcare professionals, as well as parents and guardians, can closely monitor influenza patients for any signs of abnormal behavior."
Tamiflu is an oral flu treatment. It targets the flu virus and stops it from spreading in the body. It can also reduce the chance of getting the flu. If you are already coming down with flu, Tamiflu works best if taken within 48 hours of the first flu symptoms.
Tamiflu was approved in 1999 and has been used by more than 42 million people in over 80 countries, Roche states.
Roche and the FDA continue to monitor Tamiflu safety.
Any adverse events with Tamiflu should be reported to the FDA's MedWatch program by phone at (800) FDA-1088 ((800) 332-1088) or online at www.fda.gov/medwatch.
Adverse events with Tamiflu may also be reported to Roche by phone at (800) 526-6367 or by fax at (800) 532-3931.