Many psychotic patients are treated with antipsychotic medications during acute agitation and aggressive behavior episodes in an attempt to achieve a rapid calming effect. Those medications include olanzapine, zuclopenthixol acetate, and haloperidol intramuscular administration. This study compared the effectiveness of these injections in reducing the need for restraint during agitated-psychotic episodes that include aggression. Sociodemographical and clinical data were retrieved from the electronic medical records of 179 patients who needed rapid calming while hospitalized in a mental health center with acute psychosis. The treatments administered were olanzapine intramuscular, zuclopenthixol acetate intramuscular, and haloperidol intramuscular. The assessed outcomes were rate of restraint and violent behavior. Olanzapine was found significantly more effective in reducing the need for restraint compared to zuclopenthixol acetate. No significant differences were found between haloperidol and the other two with regard to restraint. Neither were other significant differences found between the groups with regard to violent or self-harming behaviors. No significant differences were found in the rate of violent behavior and antipsychotic dosage at discharge. In conclusion, in inpatients with acute agitated psychosis, olanzapine intramuscular shows better efficacy in reducing the need for restraint, at least as compared to zuclopenthixol acetate intramuscular.