Apathy and indifference in patients on fluvoxamine and fluoxetine.

Apathy, indifference, loss of initiative, or disinhibition (without concurrent sedation or hypomania) were observed among five patients receiving the serotonin reuptake blocking antidepressants fluvoxamine or fluoxetine. These effects appeared to be dose related. They disappeared rapidly when the dose of fluvoxamine, which has a short half-life, was reduced. Fluoxetine, which has a long half-life, was more difficult to titrate. A possible relationship between mild drug-induced indifference and the therapeutic effects of serotonin reuptake blocking medication in anxiety disorders is discussed.