Adverse neuropsychiatric events associated with dexfenfluramine and fenfluramine.

1. There is a large body of evidence indicating that fenfluramines damage brain serotonin neurons in animals. 2. Little is known about potential adverse neuropsychiatric consequences in humans associated with use of fenfluramines that could potentially be related to serotonergic dysfunction. 3. The authors now report numerous cases of severe and, sometimes persistent, neuropsychiatric syndromes associated with fenfluramine use. 4. Thirty one representative cases are presented and summarized in table form. 5. Several of the cases presented suggest long-lasting deleterious effects of fenfluramines on brain serotonin function. 6. Clinicians should be vigilant for disorders of mood, anxiety, cognitive function and impulse control in patients previously exposed to fenfluramines.