Social relationships, homelessness, and substance use among emergency department patients.

The association between substance use and homelessness is multifaceted and social relationships are a complex factor linking the two. Social relationships are often critical for homelessness prevention, but they are impacted by and reciprocally affect substance use. ED-based substance use interventions should consider the high prevalence of homelessness and the impact of social relationships on the interaction between homelessness and substance use.