This chapter explores the multifaceted pharmacology of opioids and their contemporary implications in pain management. We discuss the mechanism of action of various opioid receptors and their respective clinical effects, particularly in the context of acute and chronic pain relief. We describe the significance of pharmacogenetics in opioids and emphasize how genetic variations impact individual responses to opioids, leading to differences in efficacy and dependence risk. Furthermore, the chapter explores new opioid targets and innovative approaches to mitigate associated side effects and prevent opioid use disorder. Strategies for safe prescribing practices in chronic pain management are also described, including risk assessment tools and monitoring techniques to manage addiction potential. Lastly, the chapter addresses treatment modalities for patients experiencing co-occurring chronic pain and opioid use disorder, underlining the importance of a comprehensive and individualized approach to therapy. By integrating pharmacological insights with practical applications, this chapter aims to enhance understanding of opioids’ complex role in modern medicine.