Levofloxacin-associated Encephalopathy with Severe Hyperventilation.

A 64-year-old woman with no previous mental illness took a single 500 mg tablet of levofloxacin for cystitis. Two hours later, she developed psychosis with involuntary movement and severe hyperventilation with respiratory alkalosis. Cranial magnetic resonance imaging findings were unremarkable, and an electroencephalogram revealed no epileptiform discharge. Her symptoms improved on the third day after levofloxacin was discontinued. Levofloxacin-associated encephalopathy with psychotic features is a rare adverse event. Disturbance of gamma-aminobutyric acid-ergic (GABAergic) interneurons by levofloxacin may lead to hyperventilation via dysfunction of the brainstem respiratory network. Physicians should be aware of hyperventilation as an additional serious symptom of levofloxacin-associated encephalopathy in acute settings.