BACKGROUND: Addiction is a chronic, treatable disorder, yet it carries considerable stigma. Stigmatizing language biases how clinicians view patients with substance use disorders (SUDs) and negatively affects patient care. While national medical organizations have recommended educational initiatives to reduce the stigma associated with SUDs, studies of initiatives are lacking. We aimed to improve documentation of SUDs and reduce measured stigma by teaching standardized, non-stigmatizing language. METHODS: We created an online, 25-minute interactive curriculum about vocabulary for addiction and why language matters. Before and 8 weeks after completing the curriculum, internal medicine residents viewed a video encounter between a physician and a "challenging" simulated patient with opioid use disorder, then completed a case write-up and a SUD stigma survey. We analyzed the frequency of usage of stigmatizing terms and quantified participants' stigma levels. RESULTS: During the fall of 2020, UPMC Internal Medicine residents completed the curriculum. In all, 98 participants (out of ~150) completed the pre-curriculum assessment, and 39 completed the entire course. In pre-curriculum write-ups, stigmatizing terminology was used 4 times more often than clinical terminology (30 terms per 100 write-ups versus 7.6, CONCLUSIONS: There were trends toward improvement in language, including decreased use of stigmatizing terminology and increased usage of clinical terminology, though not statistically significant. The curriculum was well-received, but the study was limited in participation by the COVID-19 pandemic. However, the simple design of the curriculum-a short, web-based module-allows for easy delivery to workers across the healthcare sector.