The decision was made after two new cases were found in which teenage boys behaved abnormally after taking the drug.

Although the ministry had insisted there was no safety problem related to Tamiflu, it decided to take the measure Tuesday upon receiving new reports of abnormal behavior.

Hawai'i will spend $2.8 million to buy anti-influenza drugs and officials signed contracts in July 2006 with drug companies to provide the antiviral drugs Tamiflu and Relenza for use in Hawai'i during a flu pandemic,

The Japanese ministry instructed Tamiflu's import-distributor, Chugai Pharmaceutical Co., to add a warning in the drug's instructions that it should not, in principle, be administered to teenage patients. The ministry also instructed the firm to provide information about Tamiflu to medical institutions.

The ministry has not suspended the use of Tamiflu to treat children under 10, but continues to call for parents to pay close attention to children who take the medication.

According to the ministry, a teenage boy who took Tamiflu in the afternoon and evening of Feb. 7 ran outside barefoot at about 2 a.m. the next morning and jumped from the second floor of his house, fracturing his right leg.

On Monday, another teenage boy who took Tamiflu in the afternoon and night jumped from a second-floor balcony of his house late at night, fracturing his right ankle, according to the ministry.

In February, there were fatal incidents in which two middle school students fell from condominium buildings after taking the drug.

In response to a series of accidents, the ministry found it is necessary to issue a warning on the use of Tamiflu, though it maintains there is no causal link between Tamiflu and abnormal behavior.

The ministry requested that teenagers refrain from using Tamiflu in principle, because it is difficult for parents to stop teenagers when they show abnormal behavior.

As for those aged 9 or younger, it is comparatively more frequent for influenza to be fatal in this age group than in others. Therefore, the ministry has not sought to suspend the use of Tamiflu for treating young children but is asking parents to keep a close eye on children for two days after they are found to have flu.

As of Oct. 31, 16 fatalities had been reported in Japan in which children under age 16 died after taking Tamiflu, according to the ministry.

Five cases have been confirmed in which children died from such causes as falling from buildings after showing abnormal behavior, including a case of a 17-year-old.