What is the best medication for pro re nata (prn) use to manage sundowning syndrome in an elderly patient with dementia that has the lowest risk of falls?

From the Guidelines

For elderly patients with dementia experiencing sundowning, low-dose risperidone (0.25-0.5 mg as needed) is generally considered the best PRN medication with the lowest fall risk profile. While all antipsychotics carry some fall risk, risperidone at these low doses tends to cause less sedation and orthostatic hypotension compared to alternatives, as suggested by the study published in the Annals of Oncology in 2018 1. Before using medication, non-pharmacological approaches should be tried first, including maintaining consistent daily routines, ensuring adequate lighting in the evening, limiting caffeine and sugar intake later in the day, and creating a calm environment. If medication becomes necessary, start with the lowest possible dose and monitor closely for side effects. The medication works by blocking dopamine receptors, helping to reduce agitation and hallucinations that can occur during sundowning.

Some key points to consider when using risperidone for sundowning in elderly patients with dementia include:

• Starting with a low dose of 0.25-0.5 mg as needed, as recommended by the study 1
• Monitoring closely for side effects, such as sedation, orthostatic hypotension, and extrapyramidal symptoms
• Using the medication for the shortest duration possible, with regular reassessment of its necessity
• Being aware of the black box warnings for increased mortality in elderly patients with dementia, as noted in the study 1

It's also important to note that other medications, such as haloperidol, olanzapine, and quetiapine, may also be used to manage sundowning symptoms, but they may have a higher risk of side effects, such as extrapyramidal symptoms, sedation, and orthostatic hypotension, as reported in the study 1. Additionally, the American Academy of Sleep Medicine clinical practice guideline published in 2015 suggests that clinicians avoid the use of sleep-promoting medications to treat demented elderly patients with irregular sleep-wake rhythm disorder (ISWRD), which is often associated with sundowning 1.

From the Research

Medication Options for Sundowning in Elderly Patients with Dementia

To manage sundowning in elderly patients with dementia, several medication options can be considered, although the evidence for their effectiveness is limited. The goal is to find a medication with the lowest risk of falls.

• Melatonin: A study published in 2000 2 found that melatonin administration can alleviate sundowning in elderly persons with dementia, reducing agitated behaviors and daytime sleepiness. Melatonin is a hormone that regulates sleep and has a relatively low risk of falls compared to other sedatives.
• Acetylcholinesterase inhibitors: These medications have been found to be helpful in ameliorating the neuropsychiatric symptoms associated with sundowning, as mentioned in a 2011 study 3. However, their effectiveness in reducing the risk of falls is not well established.
• N-methyl-d-aspartate receptor antagonists: This class of medications has also been found to be helpful in managing sundowning, as reported in a 2011 study 3. However, their impact on the risk of falls is not well understood.
• Antipsychotics: Although antipsychotics can be used to manage agitation and aggression associated with sundowning, they are generally not recommended due to their high risk of falls and other adverse effects, as noted in a 2023 study 4.

Non-Pharmacological Approaches

In addition to medication, non-pharmacological approaches such as bright light therapy, behavioral modifications, and environmental interventions can be effective in managing sundowning, as discussed in a 2011 study 3 and a 2025 study 5. These approaches may have a lower risk of falls compared to pharmacological interventions.

Considerations for Reducing the Risk of Falls

When selecting a medication for sundowning in elderly patients with dementia, it is essential to consider the risk of falls. Medications with sedative properties, such as antipsychotics, can increase the risk of falls. In contrast, melatonin and non-pharmacological approaches may have a lower risk of falls. A 2025 study 5 highlights the importance of precise diagnostic workup and individualized treatment approaches to minimize the risk of falls and other adverse outcomes.