There is concern that hydroxyzine exacerbates delirium, but a recent preliminary study suggested that the combination of haloperidol and hydroxyzine was effective against delirium. This study examined whether the concomitant use of hydroxyzine and haloperidol worsened delirium in patients with cancer.

This retrospective, observational study was conducted at 2 general hospitals in Japan. The medical records of patients with cancer who received haloperidol for delirium from July to December 2020 were reviewed. The treatments for delirium included haloperidol alone or haloperidol combined with hydroxyzine. The primary outcome was the duration from the first day of haloperidol administration to the resolution of delirium, defined as its absence for 2 consecutive days. The time to delirium resolution was analyzed to compare the haloperidol group and hydroxyzine combination group using the log-rank test with the Kaplan–Meier method. Secondary outcomes were (1) the total dose of antipsychotic medications, including those other than haloperidol (measured in chlorpromazine-equivalent doses), and (2) the frequencies of detrimental incidents during delirium, specifically falls and self-removal of drip infusion lines. The unpaired t-test and Fisher’s exact test were used to analyze secondary outcomes.

Of 497 patients who received haloperidol, 118 (23.7%) also received hydroxyzine. No significant difference in time to delirium resolution was found between the haloperidol group and the hydroxyzine combination group (log-rank test, P = 0.631). No significant difference between groups was found in either chlorpromazine-equivalent doses or the frequency of detrimental incidents.

This study showed that the concomitant use of hydroxyzine and haloperidol did not worsen delirium in patients with cancer.