Esther U. Won, MD
Geriatric Medicine (Family Medicine) Physician · Fontana, CA
Esther U. Won, MD is a geriatric medicine (family medicine) physician with a practice address in Fontana, California, and NPI 1902973803, issued on Nov 29, 2006. Check the license (California G58458, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Esther U. Won
- Credential
- MD
- Primary taxonomy
- Geriatric Medicine (Family Medicine) Physician 207QG0300X
- License number
- G58458 CA
Self-reported in NPPES; status is on the state search - Practice location
- 9961 Sierra Ave, Fontana, CA 92335
- Phone
- (909) 427-3910
- Enumerated
- Nov 29, 2006
- Record last updated
- Nov 29, 2021 (not updated in 5 years: call before relying on the address or phone)
- Entity
- Type 1 · individual
8 nearest geriatric medicine (family medicine) physician records → All 243 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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- Michael Adair, MDFamily Medicine Physician1780732651
- Berneva Adams, MDObstetrics & Gynecology Physician1376602987
Verify Esther U. Won in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G58458Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
92% fewer Medicare Part D claims than the average geriatric medicine (family medicine) physician in 2024
412 Medicare Part D claims for 48 beneficiaries, against an average of 5,222 among the 1,271 providers of this specialty who prescribed in Part D. 23 claims were for opioids.
Most prescribed
- Atorvastatin Calcium26 claims
- Pregabalin24 claims
- Tramadol Hcl21 claims
- Simvastatin17 claims
- Ondansetron Hcl14 claims
- Amlodipine Besylate13 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.
Esther U. Won among 243 geriatric medicine (family medicine) physician records in California
Esther U. Won, MD is one of 243 geriatric medicine (family medicine) physician records with a practice address in California. 76% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 6% of them.
- NPI issued2006 · 6% of these records are older, 53% newer
- In a Medicare fileYes · 76% of these records are
- In the CMS Doctors and Clinicians fileNo · 46% of these records are
- Record last updated2021 · 69% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207QG0300X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Geriatric Medicine (Family Medicine) Physician providers in California
There are 243 geriatric medicine (family medicine) physician records in California.
All 243 in California → Every provider in Fontana → Geriatric Medicine (Family Medicine) Physician nationwide →
The 8 geriatric medicine (family medicine) physician records with the nearest ZIP codes
- Kent Ahn, MDFontana, CA 923351083762017
- Israel Coutin, MDFontana, CA 923351790852663
- Juanito Garlitos, MDFontana, CA 923351780751644
- Karisa Jahn, D.O.Fontana, CA 923351346531027
- Kamal Kejriwal, MDFontana, CA 923351336210392
- Helen Lee, MDFontana, CA 923351336210244
- Norman Ragaza, MDFontana, CA 923351508925249
- Ruby Singh, DOFontana, CA 923351083766463
Common questions
What is Esther U. Won, MD's NPI number?
Esther U. Won, MD's National Provider Identifier (NPI) is 1902973803, issued on Nov 29, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Esther U. Won, MD located?
The NPPES record lists a practice address at 9961 Sierra Ave, Fontana, CA, 92335. Phone: (909) 427-3910. Providers update this record themselves, so call before visiting.
How can I verify Esther U. Won, MD's license?
NPPES lists California license number G58458, 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 Esther U. Won, MD prescribe under Medicare Part D?
In 2024, Esther U. Won, MD had 412 Medicare Part D claims for 48 beneficiaries; the average among geriatric medicine (family medicine) physician prescribers was 5,222. 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.