Brazil´s Unified Health System (SUS) organizes Primary Health Care (PHC) through the Family Health Strategy (FHS), its main territorial model. Community Health Workers (CHWs) playing a pivotal role in direct engagement within communities. Their activities include home visits, vulnerability assessment, and family follow-up, fostering continuity of care. This proximity positions CHWs as key actors in the early detection of health risks, including those related to alcohol and drug use. SUS adopts harm reduction as a guiding principle, aligned with human rights. Understanding CHW´s responsibilities and challenges is essential to strengthen prevention and person-centered care strategies in PHC.To analyze and synthesize evidence on the role of Community Health Workers in the early identification of health problems related to alcohol and other drug use, potentialities, barriers, and strategies to improve CHW performance in Primary Health Care.A narrative review was conducted, including institutional documents and qualitative studies on harm reduction, practices and professional performance within the Family Health Strategy. Materials addressing CHW work, harm reduction policies, and the management of drug-related problems were included. The analysis emphasized convergent themes, considering the predominance of qualitative approaches and their implications for practice.The reviewed studies indicate that CHWs occupy a strategic position in the early identification of drug-related health problems due to their close relationship with families, regular home visits, and knowledge of the territory. Despite this, actions remain limited and are frequently restricted to referrals. Barriers include stigma, moralistic views, work overload, lack of matrix support, and insufficient continuing education.This review highlights the significant potential of CHWs to support prevention and care related to drug use; however, this potential is constrained by structural and subjective barriers. These challenges reflect systemic gaps in training, support, and integration with specialized services, which hinder the implementation of harm reduction principles.This review highlights the significant potential of CHWs to support prevention and care related to drug use; however, this potential is constrained by structural and subjective barriers. These challenges reflect systemic gaps in training, support, and integration with specialized services, which hinder the implementation of harm reduction principles.