A 21-year-old black woman, with no prior psychiatric history, presented at the Emergency Department of our hospital with an acute onset of psychotic symptoms.
These symptoms included paranoid delusion (she was convinced that her sister had made witchcraft against her and her boyfriend was cheating on her), psychomotor agitation, and initial insomnia.
The symptoms appeared four days after she was started on antituberculous therapy including isoniazid 300 mg/day, rifampicin 600 mg/day, ethambutol 1200 mg/day, and pyrazinamide 1500 mg/day, for pleural tuberculosis. She was also on pyridoxine 200 mg/day and thiamine 100 mg/day for prophylaxis against neuropathy associated with isoniazid.
In addition to the recently diagnosed pleural tuberculosis, the patient had no previous medical history and no history of substance abuse.
At mental state examination, she was poorly cooperative and suspicious, displayed psychomotor agitation, moving around constantly and had anxious humour and paranoid delusions. No errors of perception were detected and judgement regarding the morbid nature of her condition was impaired.
On examination, vital signs were stable and the physical signs, including neurological examination, were unremarkable. Testing including a complete blood count, chemistry panel, liver and thyroid function tests, and a urine toxicology screen was normal. A computed tomography scan of the head was obtained and showed no abnormality.
An initial diagnosis of drug-induced psychosis was made, once we considered the possibility that her psychotic symptoms could have been secondary to isoniazid, and the patient was admitted to our inpatient unit. All antituberculous therapy was discontinued and she was started on olanzapine 15mg/day.
By the seventh day, the psychotic symptoms had remitted, and the patient presented full insight into her clinical condition. The antituberculous therapy was reintroduced by the following order: rifampicin 600 mg/day at day 10, pyrazinamide 1500 mg/day at day 12, and ethambutol 1200 mg/day at day 17. Since these three antibacterial agents have efficacy in the treatment of pleural tuberculosis, it was decided not to introduce isoniazid.
At day 10, the antipsychotic started to be progressively reduced and by the time the patient was discharged (after 21 days of hospitalization) she was only taking olanzapine 5 mg/day and the antituberculous therapy.
The patient stopped taking olanzapine one week after discharge and at the four-week follow-up in outpatient consultation; she remained stable, with no recurrence of psychotic symptoms. The fast remission of symptoms and the good clinical outcome further supported our diagnosis of drug-induced psychosis.