Introduction:
Low social support and self-efficacy can result in negative impact on physical and mental well-being. Therefore, the present study was carried out to investigate social support, self-efficacy, and factors affecting adherence to medication in people living with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS).

Material and methods:
This descriptive co-relational study was performed among HIV/AIDS individuals over the age of 18 years, who were referred to the Behavioral Diseases Counseling Center in Kerman City, Iran, in 2017. In this regard, 117 patients were selected by census method and categorized into intervention and control groups. Later, we used AIDS Clinical Trials Group (ACTG) questionnaire to collect required data, and then before and 3 months after the intervention to assess medication adherence. The intervention was included eight 60-90 minutes training sessions, over the course of 14 weeks, based on Information-Motivation-Behavioral Skills (IMB) model.

Results:
The main reasons for ART non-adherence were forgetfulness in taking antiretroviral therapy (ART) (17.9%), away from home, depression (9.4%), and transportation problems (8.5%). Signifi­cant relationship was observed after the intervention based on IMB model with self-efficacy (0.000) and social support (0.010).

Conclusions:
The IMB model can be effective in promoting self-efficacy and social support in HIV patients. However, the information model was ineffective for major problems that had reduced adherence to medication regimen, such as forgetting to take medications, depression, and transportation issues.