People who have HIV and a substance use disorder and are incarcerated have a greater chance of doing well on their antiretroviral (ARV) medications when they get out of jail or prison if they are given monthly injections of naltrexone starting just before their release. This long-acting drug is approved by the Food and Drug Administration to treat alcohol use disorder (AUD) and opioid use disorder (OUD). A recent pair of studies included about 200 people with AUD or OUD leaving jail for Northeastern communities. After adjusting the data for various factors, the study authors found that receiving naltrexone versus a placebo was associated with a 4.5-fold increased likelihood of having an undetectable viral load six months post-release among those with AUD and a 2.9-fold increased risk among those with OUD. The participants did not experience any serious adverse health events.