Background: Assessment and management of pain in elderly people with cognitive impairment is particularly challenging. Physiological changes due to aging as well as comorbidities and polypharmacy are responsible for a complex clinical approach. Concomitantly, in cognitive impairment, including advanced dementia, changes in central nervous system along with changes in the peripheral nervous system due to aging have a significant impact in pain perception. Often clinicians decide to prescribe opioids in order to relief pain, also without a clear indication. Aim: This review aims to investigate the effect of opioids in elderly patients with cognitive impairment. Methods: A literature search of PubMed/Medline, Scopus, and Cochrane databases was conducted using keyword searches to generate lists of articles which were screened for relevance by title and abstract to give a final list of articles for full-text review. Further articles were identified by snowballing from the reference lists of the full-text articles. Results: This review discuss the complex physiological and pharmacological changes in elderly as well as the neurological changes that affect pain perception in this population. Additionally, it focuses on cognitive impairment and pain in Alzheimer’s disease and other dementias, the pain assessment in the elderly with cognitive impairment as well as the safety of opioid use in elderly. Information regarding opioid prescription in nursing homes as well as recorded indications for opioids use, type and dosing of opioid and compliance of treatment in advanced dementia are also provided. Conclusions: Opioid prescription in elderly population with cognitive impairment is particularly complex. All healthcare professionals involved in the care of such patients, need to be aware of the challenges and strive to ensure analgesic use is guided by appropriate and accurate pain assessment.