Dr. Oh received his undergraduate degree from Columbia University in New York City and his medical degree from Tufts University School of Medicine in Boston.

He completed his internal medicine residency at Rhode Island Hospital/Brown Medical School where he also served as the chief medical resident. Dr. Oh then completed his gastroenterology fellowship at Beth Israel Deaconess Medical Center in Boston. During his gastroenterology fellowship, Dr. Oh earned his Masters degree in Medical Science from Harvard Medical School. He was the recipient of 2002 AASLD/Schering Advanced Hepatology Fellowship Award.

Upon completion of his fellowship, he joined the faculty at Harvard Medical School as an Instructor of Medicine and as a staff physician at Beth Israel Deaconess Medical Center. He also served as the fellowship director of hepatology program at Beth Israel Deaconess Medical Center before joining Tacoma Digestive Disease Center.