Insights About Nitazene Use From Self-reported Experiences on Reddit Obtained Using Natural Language Processing

INTRODUCTION: Nitazenes are an emerging class of highly potent synthetic opioids not approved for clinical use. Knowledge of nitazene-associated practices and clinical effects remains limited. Reddit contains nitazene-related discussions describing self-reported experiences. We analyzed nitazene mentions to characterize these experiences. METHODS: Nitazene-mentioning posts between 01/2019 and 10/2025 were extracted via natural language processing-based lexical filters, and a random sample of 293 mentions was qualitatively reviewed and annotated for themes consolidated via consensus discussion. Repeated findings more specific than themes were synthesized as subthemes, and a validated GPT-4o-based pipeline was applied to all mentions to forecast the theme distribution. RESULTS: A total of 31,638 mentions were extracted; frequency increased between 2022 and 2024 (mean 584 mentions/month, P<0.01 increase compared with 2019-2021's mean of 197 mentions/month). Ten themes were curated, with source (31.3%), potency and dose (26.5%), and uncertainty (25.9%) most prevalent in the annotated sample. Across the full dataset, automated characterization predicted that general experience (44.7%), general comment (37.9%), and potency and dose (27.6%) were the most prevalent thematic labels. Nine subthemes included information about counterfeit pills, withdrawal management difficulties, motivating factors for use, benzodiazepine adulteration, and vascular injury associated with intravenous administration. DISCUSSION: Increasing nitazene mentions on Reddit may reflect increasing interest and use. Thematic characterization identified patterns in nitazene use, effects, and distribution relevant to clinical practice and public health. Insights provided by subthemes align with laboratory potency assessments and emerging evidence from case series and health alerts. CONCLUSION: These findings can inform public health monitoring, overdose prevention, and clinical characterizations of nitazene use.