Evidence-based strategies to guide HIV prevention for people who use substances can be grouped into approaches that lower infectiousness among substance users living with HIV and those that prevent HIV acquisition among those who are uninfected. Dramatic successes in HIV prevention involving access to antiretroviral therapy (ART), opioid substitution therapies, and needle and syringe exchange programs have reduced both prevalence and incidence in the United States for people who use injection drugs, and modeling studies suggest that scale-up of these approaches will have a parallel impact worldwide. Medical HIV-prevention strategies that reduce infectiousness ("treatment as prevention" or early ART initiation) and that block HIV acquisition (pre-exposure prophylaxis, post-exposure prophylaxis) can constitute key elements of novel combination HIV-prevention approaches to the goals of reducing infectiousness and reducing acquisition of HIV among people who use substances. For individuals who use substances but do not inject, drug dependence treatments as HIV prevention have a meager evidence-base, with most consistent findings being reduction of sexual transmission behaviors that correspond with reductions in substance use, though not with prevention of HIV transmission. This approach may have value, however, when working with groups of substance users who face high rates of HIV prevalence and incidence. Some evidence exists to support HIV prevention interventions that target reduction of sexual risk behaviors in the setting of active stimulant use.
