Trust, place, and polysubstance use shape the feasibility of community-based drug checking in the Southern United States: A mixed-methods implementation study

Background The unregulated drug supply in the United States (US) is increasingly volatile, with rising contamination by fentanyl and xylazine, contributing to overdose and drug-related morbidity and mortality. Drug checking is a promising harm reduction strategy; yet, little is known about how social trust, place, and patterns of polysubstance use influence the feasibility and implementation of community-based drug checking in the Southern US, where punitive drug policies and institutional mistrust remain prominent. Methods We conducted a multiphase, sequential, exploratory, and explanatory mixed-methods, community-engaged implementation study in Fulton County, Georgia. The theoretical framework COM-B (Capability, Opportunity, Motivation–Behavior) was used to examine individual- and community-level determinants of engagement among people who use drugs. Quantitative surveys were administered to people who use drugs (PWUD; N = 164), recruited from syringe services programs, nightlife settings, festivals, and informal housing environments, to assess drug use contexts, drug-checking behaviors, and trust in drug sources, and a subset of participants completed semi-structured qualitative interviews (n = 16). Survey findings were analyzed descriptively and used iteratively to inform qualitative data collection. Qualitative data were analyzed using rapid thematic analysis and integrated across frameworks. Results Nearly two-thirds of PWUD in the quantitative sample (62%) reported never testing their drugs despite high awareness of overdose risk. Trust in known drug sources was a central theme reducing the perceived need for testing, while distrust of law enforcement and institutions constrained engagement with formal drug-checking services. Polysubstance use was widespread and intentional, complicating the perceived utility of single-analyte testing tools. Conclusions This study demonstrates that while community drug checking is urgently needed in Fulton County, its successful implementation is constrained by stigma, trust in source, and limited drug education. Legal reforms and expanded access to testing tools alone are insufficient to ensure uptake of drug checking.