The pathophysiology of delirium is not fully understood, and is likely to be complex. [1-3] Pharmacological treatment of delirium has evolved empirically and relies predominantly on antipsychotics. In a palliative situation where there is risk of harm and significant distress to patient and caregivers, sedation may also be a goal of treatment, and sedatives are frequently used. There is little guidance from the literature regarding when antipsychotics should be commenced, how they should be titrated, whether they actually alter the outcomes of the delirium episode, and whether they are equally effective in hypoactive and hyperactive delirium. [4-5]
What is known
Systematic reviews of antipsychotics for the pharmacological management of delirium have been completed. [1, 4-12] The evidence comes mainly from small studies, few of which were done in palliative care populations. Antipsychotics have been studied as both treatment for established delirium and as prophylaxis. Whilst the evidence from systematic reviews suggests a benefit in the treatment of delirium, it is not robust enough to support specific recommendations. Practice therefore continues to be based on expert opinion.
None of the systematic reviews has identified clinically significant differences between haloperidol and atypical antipsychotics. The findings are limited by the lack of placebo-controlled studies. Improvement as a result of the natural history of delirium cannot be excluded.
Limited data from the included studies suggests that haloperidol (at higher doses, i.e., greater than 4.5mg per day) may be associated with slightly more side effects than atypical agents; however few of the studies examined adverse events systematically.
A systematic review specifically focusing on treatment of delirium at the end of life notes that there is no evidence to support the use of benzodiazepines, barbiturates, phenothiazines or propofol in treatment of delirium in palliative care. Nor was any evidence available to support the practices of opioid switching or artificial hydration in treating delirium. 
What it means in practice
- An assessment for delirium should first identify potentially reversible causes and attempt to treat them.
- Pharmacological management of delirium is at present based on expert opinion and, on that basis, low dose haloperidol can be recommended as first line treatment.