Objective Common mental disorder has a high prevalence in the general population worldwide. One in four patients visiting any health services has at least one mental disorders and negatively impacts quality of life, physical wellbeing, poor level of functioning, and poor medication adherence. However, research into common mental illness and associated factors among people with outpatient medical patients in low and meddle-income countries is limited. Therefore, this study aimed to explore common mental disorder and associated factors among persons with outpatient medical illness in Ethiopia. Result The prevalence of common mental disorder was found to be 39.2% with [95% CI 34.2%, 44.1%]. In the multivariate logistic regression, female sex [AOR: 2.03, 95% CI 1.28, 3.22], poor social support [AOR: 3.56 (95% CI 2.21, 5.73)], Diabetes mellitus [AOR: 5.25, 95% CI 2.35, 11.73], and substance use [AOR: 1.93, 95% CI 1.23, 3.04] were factors significantly associated with common mental disorder. Electronic supplementary material The online version of this article (10.1186/s13104-019-4394-x) contains supplementary material, which is available to authorized users.

Introduction: Mental health problems appear to be increasing in importance in Africa. Mental and substance use disorders were the leading cause of yearly lived with disability in Sub-Saharan Africa. Evidence from previous studies shows considerable variation in the prevalence of these disorders. The most acceptable explanation for this wide variation is likely to be the fact that socio cultural factors are major determinants of mental disorders. Therefore a mental disorder has to be understood in a specific setting to develop effective and tailored interventions. Objective: The objective of this study was to determine the prevalence and associated factors of common mental disorders among adult residents in Silte Zone, southern Ethiopia Methods: Community based cross-sectional study was conducted in the study area. A total of 1178 adults were selected by using a three-stage systematic sampling technique. The Self-Reporting Questionnaire (SRQ-20) was used to determine the prevalence of common mental disorders. Data were analyzed by using SPSS version 20. Both bivariate and multiple logistic regression analyses were employed to identify factors associated with common mental disorders. Results: The prevalence of common mental disorders among adults found to be 39.7%. Increased age (OR = 1.114; 95% CI = 1.095, 1.134), being female (OR = 9.421; 95% CI = 5.947, 14.926), poor social support (OR = 1.987; 95% CI = 1.358, 2.907) and having life threatening experience (OR = 2.162; 95% CI = 1.825, 2.562) were significantly associated with common mental disorders. Conclusion: In the study, the magnitude of common mental disorders remains high in the study area. Increased age, being female, poor social support and having life-threatening experience were significantly associated with common mental disorders.