TOKYO - Japan is looking into whether two influenza drugs other than Tamiflu are linked to abnormal behavior including cases of young patients screaming and one boy attempting to jump off a balcony, the Health Ministry said on Wednesday.

Japan in March warned against prescribing Tamiflu to those aged 10 to 19 after more than 100 people, mostly young, showed signs of abnormal behavior after taking the drug.

Doctors investigating Tamiflu also found 16 cases of patients showing side effects after taking Relenza, an inhaled drug made by GlaxoSmithKline, and another influenza drug, amantadine, a report released by the Health Ministry showed.
Of the cases, 13 involved patients under 20 years old. Ten involved patients who had taken Relenza and the other six were linked to those who had taken amantadine.

Japan has launched a full investigation into whether there is any causal link between Tamiflu, made by Roche Holding AG, and neuropsychiatric problems.

Roche has said no causal relationship has been established, and doctors have said influenza itself can cause abnormal behavior.

Tamiflu, known genetically as oseltamivir, can treat the symptoms of regular seasonal influenza and it is seen as one of the best defenses against a possible bird flu pandemic.