Purpose of Review <p>The OPRM1 A118G polymorphism, a single nucleotide variation in the mu-opioid receptor (MOR) gene, has been investigated for its role in opioid efficacy, addiction vulnerability, opioid-related adverse effects, and patient behavior. This review synthesizes recent findings, with a focus on clinical implications for patients with this polymorphism.</p> Recent Findings <p>Recent research into the OPRM1 A118G polymorphism continues to explore the variant G allele’s impact on opioid response in pain management. Though guidelines do not yet recommend clinical adoption of testing for this polymorphism, recent studies have begun to show the potential value of incorporating genotype-guided therapy for G allele carriers.</p> Summary <p>The OPRM1 A118G polymorphism presents a complex clinical picture with implications for therapeutic outcomes. Its diverse effects underscore the potential for personalized treatment, particularly for individuals with the AG/GG genotype. Future research into optimized medical, procedural, and behavioral therapies for G allele carriers will be crucial in advancing genotype-guided treatment.</p>