ImportanceAlthough incarcerated individuals experience higher rates of chronic conditions, little is known regarding the use of prescription medications in jails and prisons in the US.ObjectiveTo characterize treatment with prescription medications in jails and state prisons relative to noncorrectional settings in the US.Design, Setting, and ParticipantsThis cross-sectional analysis using 2018 to 2020 data from the National Survey on Drug Use and Health (NSDUH) estimated the prevalence of disease among recently incarcerated and nonincarcerated adults in the US. The study used 2018 to 2020 IQVIA’s National Sales Perspective (NSP) to quantify the distribution of medications to incarcerated and nonincarcerated populations. The NSP provides national dollar and unit sales of prescription medications across multiple distribution channels, including prisons and jails. The study population included incarcerated and nonincarcerated individuals from NSDUH. Seven common chronic conditions were assessed. Data were analyzed in May 2022.ExposuresMedications being sent to correctional facilities vs all other settings in the US.Main Outcomes and MeasuresThe main outcomes were distribution of medications to treat diabetes, asthma, hypertension, hepatitis B and C, human immunodeficiency virus (HIV), depression, and severe mental illness to incarcerated and nonincarcerated populations.ResultsThe proportion of pharmaceuticals distributed to jails and state prisons to treat type 2 diabetes (0.15%), asthma (0.15%), hypertension (0.18%), hepatitis B or C (1.68%), HIV (0.73%), depression (0.36%), and severe mental illness (0.48%) was much lower compared with the relative burden of disease among this population. The incarcerated population in state prisons and jails accounted for 0.44% (95% CI, 0.34%-0.56%) of estimated individuals with diabetes, 0.85% (95% CI, 0.67%-1.06%) of individuals with asthma, 0.42% (95% CI, 0.35%-0.51%) of hypertension, 3.13% (95% CI, 2.53%-3.84%) of hepatitis B or C, 2.20% (95% CI, 1.51%-3.19%) of HIV, 1.46% (95% CI, 1.33%-1.59%) of depression, and 1.97% (95% CI, 1.81%-2.14%) of severe mental illness. After adjusting for disease prevalence, the relative disparity was 2.9-fold for diabetes, 5.5-fold for asthma, 2.4-fold for hypertension, 1.9-fold for hepatitis B or C, 3.0-fold for HIV, 4.1-fold for depression, and 4.1-fold for severe mental illness.Conclusions and RelevanceIn this cross-sectional, descriptive study of the distribution of prescription medications for chronic conditions in jails and state prisons, the findings suggest that there may be underuse of pharmacological treatment in correctional facilities relative to the nonincarcerated population. These findings, which require further investigation, may reflect inadequate care in jails and prisons and represent a critical public health issue.