[Isoniazid-induced visual hallucinosis].

Introduction: Isoniazid is the antituberculosis drug that causes psychiatric manifestations most often. Their incidence is nonetheless rare: a review of the literature found only 16 cases. Only one author has reported hallucinosis, defined by isolated sensorial symptoms, and perceptions not believed to be the reality of the object.

Case: We report a case of a 42-year-old woman, a nonsmoker with no particular history and with lymph node tuberculosis. Three weeks after beginning antituberculosis treatment (isoniazid, rifampicin, pyrazinamide and streptomycin), visual hallucinosis and a headache appeared. The symptoms disappeared when Isoniazid was stopped and an anxiolytic drug prescribed. These findings suggest that these effects were due to isoniazid.

Discussion: Two mechanisms may explain these psychiatric manifestations: vitamin B6 deficiency or interference between isoniazid and bioamine metabolism.