Cases of sudden and unexpected death have been reported in association with the administration of Haloperidol injection. The nature of the evidence makes it impossible to determine definitively what role, if any, Haloperidol injection played in the outcome of the reported cases. The possibility that Haloperidol injection caused death cannot, of course, be excluded, but it is to be kept in mind that sudden and unexpected death may occur in psychotic patients when they go untreated or when they are treated with other antipsychotic drugs.
Two hundred forty-seven participants (mean [SD] age,  years; 85 women [%]; 218 with cancer [%]) were included in intention-to-treat analysis (82 receiving risperidone, 81 receiving haloperidol, and 84 receiving placebo). In the primary intention-to-treat analysis, participants in the risperidone arm had delirium symptom scores that were significantly higher than those among participants in the placebo arm (on average Units higher; 95% CI, -; P = .02) at study end. Similarly, for those in the haloperidol arm, delirium symptom scores were on average Units higher (95% CI, -; P = .009) than in the placebo arm. Compared with placebo, patients in both active arms had more extrapyramidal effects (risperidone, ; 95% CI, -; P = .03; and haloperidol, ; 95% CI, -; P = .01). Participants in the placebo group had better overall survival than those receiving haloperidol (hazard ratio, ; 95% CI, -; P = .003), but this was not significant for placebo vs risperidone (hazard ratio, ; 95% CI, -; P = .14).
Haloperidol use may lead to the development of symptoms that resemble Parkinson's disease, but that are not caused by Parkinson's. These symptoms may include a taut or mask-like expression on the face, drooling, tremors, pill-rolling motions in the hands, cogwheel rigidity (abnormal rigidity in muscles, characterized by jerky movements when the muscle is passively stretched), and a shuffling gait. Taking the anti-Parkinson drugs benztropine mesylate or trihexyphenidyl hydrochloride along with haloperidol help to control these symptoms. Medication to control Parkinsonian-like symptoms may have to be continued after haloperidol is stopped. This is due to different rates of elimination of these drugs from the body.