Tamiflu, one of the front-line drugs against flu, can kill, a new warning from America's drug regulator, the Food and Drug Administration (FDA), has revealed this week.
The drug can cause hallucinations, delirium or abnormal behaviour which sometimes "results in fatal outcomes," the FDA has said.
These new reactions have been discovered by doctors who suspected the drug of being the cause, and so there's no way of knowing how widespread the problem is.
Tamiflu's manufacturer, Roche, has this week written to every practitioner in the USA about the new reactions, and it has been instructed to change the warnings on the drug's patient information sheet.
The drug is also being used as a defence against avian flu, and governments around the world have bought billions of dollars worth of supplies to be used to protect key workers.
(Source: FDA web site).