Background: Opioid overdose incidence in Myanmar has not been systematically measured. We quantified individual risk factors of overdose, overdose incidence and mortality, and examined predictors of pre‑overdose engagement with harm reduction services.

Methods: Electronic registers from 21 Asian Harm Reduction Network–Best Shelter (AHRN–BS) sites in Sagaing, Kachin, and northern Shan (2014–2025) were linked. Incidence and mortality were calculated with the exact Poisson method. A retrospective cohort of 155,875 clients—65,089 people who inject drugs—was analyzed with modified Poisson regression to estimate adjusted prevalence ratios (aPR) for overdose; cases occurring in 2022–2025 were further analyzed for predictors of past‑year service engagement.

Results: Registers captured 3472 verified opioid overdoses in 2913 persons. Among people who inject drugs, pooled incidence was 16.8/1000 person‑years (95 % CI 16.2–17.5) and overdose mortality 0.5/1000 person‑years (0.4–0.7). Current injecting without opioid‑agonist therapy (OAT) carried an aPR 8.1 (95 % CI 6.1–10.6) relative to recent non‑injecting use, rising to aPR 10.7 (95 % CI 7.8–14.8) among those who also received OAT. Three‑quarters of overdoses (2598) occurred in persons not enrolled in harm reduction programs; incidence among enrolled clients was 5.7/1000 person-years (95 % CI 5.2–6.2). Migrants were less likely to have accessed services in the year preceding overdose (aPR 0.82, 95 % CI 0.68–0.98). Alcohol was reported in 70.5 % of events and stimulants in 7.2 %.

Discussion: Opioid overdose is common and disproportionately affects people outside existing programs. Expanding peer‑led and mobile outreach, tailoring referral pathways for migrants, broadening community naloxone distribution, and securing sustained domestic financing are urgent priorities.