Edward Ungseok Oh, MD
Internal Medicine Physician · Fontana, CA
Edward Ungseok Oh, MD is an internal medicine physician with a practice address in Fontana, California, and NPI 1376284026, issued on Apr 6, 2022. Check the license (California A203095, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Edward Ungseok Oh
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- A203095 CA
Self-reported in NPPES; status is on the state search - Practice location
- 9961 Sierra Ave, Fontana, CA 92335
- Phone
- (909) 427-5000
- Enumerated
- Apr 6, 2022
- Record last updated
- Oct 31, 2025
- Medicare enrollment
- Enrolled (PECOS I20250919001902); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 9961 Sierra Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Edward Ungseok Oh in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A203095Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
87% fewer Medicare Part D claims than the average internal medicine physician in 2024
414 Medicare Part D claims for 85 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D.
Most prescribed
- Atorvastatin Calcium45 claims
- Spironolactone15 claims
- Famotidine14 claims
- Metoprolol Tartrate14 claims
- Eliquis12 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Bills Medicare through one group practice
- Southern California Permanente Medical GroupOntario, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Edward Ungseok Oh among 17,696 internal medicine physician records in California
Edward Ungseok Oh, MD is one of 17,696 internal medicine physician records with a practice address in California. 79% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2022, is newer than 95% of them.
- NPI issued2022 · 95% of these records are older, 2% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated2017 · median 2004 among the 11,065 with a school on file
- Record last updated2025 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
111 internal medicine physician records list a practice address in Fontana
They are 111 of the 3,012 NPPES records with a practice address in Fontana, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Fontana → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Te-Ie Lee, M.D.Fontana, CA 923351982613931
- Hollis Lee, MDFontana, CA 923351588736060
- Hoveda Mufti, M.D.Fontana, CA 923351598871493
- J Duc Nguyen, M.D.Fontana, CA 923351427018456
- Joseph Paredes, MDFontana, CA 923351457422420
- Ramesh Patel, MDFontana, CA 923351750480810
- Alex Quan, MDFontana, CA 923351659442630
- Gregory Shimizu, MDFontana, CA 923351154492130
Common questions
What is Edward Ungseok Oh, MD's NPI number?
Edward Ungseok Oh, MD's National Provider Identifier (NPI) is 1376284026, issued on Apr 6, 2022. An NPI identifies a provider in billing; it is not a license.
Where is Edward Ungseok Oh, MD located?
The NPPES record lists a practice address at 9961 Sierra Ave, Fontana, CA, 92335. Phone: (909) 427-5000. Providers update this record themselves, so call before visiting.
How can I verify Edward Ungseok Oh, MD's license?
NPPES lists California license number A203095, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Edward Ungseok Oh, MD prescribe under Medicare Part D?
In 2024, Edward Ungseok Oh, MD had 414 Medicare Part D claims for 85 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.