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.

Somnambulism or sleepwalking could be explained by dysfunction in the regulation of slow-wave sleep. It may be caused by drugs; in the literature, cases of somnambulism that occurred by olanzapine and lithium have been reported.

Discuss the association between somnambulism and Hydroxyzine.

We will discuss the case of a patient with bipolar disorder treated with olanzapine and lithium who experienced episodes of somnambulism after adding Hydroxyzine.

A 42-year-old woman, with no history of somnambulism, followed in our department for a bipolar disorder type 1, treated with 750 mg of lithium and 20 mg of olanzapine. During her usual control, she reported insomnia Hydroxyzine was added at the dose of 50 mg. At the next medical appointment, she said that her husband had noticed that she waked up at night and she eats, she ambulates and searches things. Episodes that the patient did not remember. She was tranferd to the neurolgic departement. She did a neurological exam, an electroencephalogram, and a brain scan, witch were normal. The polysomnography confirmed the diagnosis. The neurologist retained the diagnosis of somnambulism induced by Hdroxizine regarding the chronology of the symptoms. The somnambulism ceased after stopping Hydroxyzine.

Lithium and olanzapine were associated with the occur of somnambulism, but hydroxyzine had never been reported as a somnambulism drug inducing. Drug interaction may explain this phenomenon.

No significant relationships.