Background: Isoniazid is the first line agent for the treatment of tuberculosis. Psychosis is a known complication of isoniazid therapy, although infrequent. Case report: One female and two male patients aged 35 years, 55 years and 60 years respectively developed psychosis following isoniazid administration. All the three received 300 mg of isoniazid daily for the management of pulmonary tuberculosis. High dose of isoniazid and low body mass index were identified as the common risk factor for the development of isoniazid associated psychosis. The incidence, possible pathogenesis, risk factors and treatment options are discussed. Conclusion: Isoniazid psychosis is a major complication, which if recognized early can be effectively treated.
Key words: Adverse drug reaction, Anti-tubercular therapy, Case series, Isoniazid, Psychosis.