Organic hallucinosis in patients receiving high doses of opiates for cancer pain.

We report 4 patients who developed organic hallucinosis while receiving opiate analgesics for cancer pain. In all patients, the symptoms rapidly responded to haloperidol and change in the type of opiate. The hallucinations were exclusively visual. Cognitive status, determined by the Mini-mental State Questionnaire (MMSQ), was normal in all patients. Organic hallucinosis occasionally occurs in patients receiving opiates and can be a major source of distress for patients and their families.