John Lah, MD


Dr. Lah had been a practicing physician in Whittier, California for 13 years before joining United Medical Doctors in January 2022.

He is a graduate of the University of California San Diego and attended medical school at New York Medical College. Dr. Lah then completed his Internal Medicine residency and Gastroenterology Fellowship at the University of California Irvine Medical Center in Orange, CA.

Dr. Lah initially began his practice at Kaiser Permanente in Walnut Creek and Antioch, CA for 2 years. During his tenure with Kaiser Permanente he served as Assistant Chief of Gastroenterology at Walnut Creek and Antioch. Dr. Lah moved to Southern California and joined a private practice in Whittier in 2008. During that time he was on medical staff at PIH Health – Whittier eventually joining with PIH Health in 2011 as one of the primary gastroenterologist. Dr. Lah served for a few years as the GI section chief at PIH Health – Whittier as well.

During his time at PIH Health, he worked closely with the Colon Cancer Prevention Alliance, a program designed to allow patients and members of the community easy access to colon cancer screenings. He also served as a clinical instructor for the PIH Health Family Medicine Residency Program for the 13 years he was a part of PIH Health until his departure for United Medical Doctors in January 2022. Teaching had been an important part of his practice and he takes pride in being given teaching awards during his time at PIH Health by the residents within the program.

Dr. Lah and his staff are committed to providing professional, compassionate, efficient, and quality digestive health care to patients.

Dr. Lah’s mission is to educate patients about their digestive health needs so that they can be active participants in the process of managing and treating their own digestive ailments.

Board Certifications
American Board of Gastroenterology
American Board of Internal Medicine

Medical Education
New York Medical College
University of California San Diego

University of California Irvine

Fellowship Training
University of California Irvine

Office Locations
Los Alamitos – T: (562) 430-4449 | 3851 Katella Ave., Ste., 205, Los Alamitos, CA 90720
Huntington Beach – T: (714) 963-1600 | 19582 Beach Blvd., Ste. 218, Huntington Beach, CA 92647
Fountain Valley – T: (714) 962-7705 | 18111 Brookhurst St., Ste 5200, Fountain Valley, CA 92708