Opioid Addiction Medicine in Nigeria: Bridging Clinical Gaps in a Silent Epidemic-A Narrative Review.

Opioid use disorder (OUD) is an emerging public-health challenge in Nigeria, driven largely by non-medical use of tramadol and codeine and compounded by limited access to evidence-based care. This narrative review synthesises evidence on the epidemiology, patterns, harms and treatment gaps for OUD in Nigeria and identifies priorities for policy and research. We searched PubMed/MEDLINE, Embase, PsycINFO, the Cochrane Library, African Journals Online, Google Scholar and grey literature from 2005 to 2024 for Nigerian data on non-medical opioid use, clinical harms, opioid agonist therapy (OAT) services, barriers and community supports. Findings were thematically synthesised using Braun and Clarke's framework, with quality appraisal using Joanna Briggs Institute tools and the SANRA scale. Thirty studies were included. The 2019 national drug use survey estimated past-year opioid use at 4.7% (approximately 4.6 million people), with institution-based surveys reporting high lifetime misuse among undergraduates. Reported harms included overdose, seizures, psychiatric comorbidity and injectable pentazocine dependence with severe soft-tissue infections. OAT availability remains highly centralised, with limited community recovery infrastructure. Nigeria's OUD burden is substantial but unevenly characterised, highlighting the need to decentralise OAT, integrate addiction training, strengthen surveillance and expand community supports.