Registry data as of Aug 27, 2026

John Gahagan, M.D.

Surgery Physician · Pleasanton, CA

John Gahagan, M.D. is a surgery physician with a practice address in Pleasanton, California, and NPI 1558629493, issued on Apr 29, 2012. Check the license (California A126753, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.

Record from CMS NPPES, loaded Aug 27, 2026 · Medicare files 2023 and 2024 · method · Verify with CMS →

NPPES recordas of Aug 27, 2026
1558629493
Name
John Gahagan
Credential
M.D.
Primary taxonomy
Surgery Physician 208600000X
License number
A126753 CA
Self-reported in NPPES; status is on the state search
Practice location
5725 W Las Positas Blvd Ste 100, Pleasanton, CA 94588
Phone
(925) 734-8130
Enumerated
Apr 29, 2012
Entity
Type 1 · individual
Public record from CMS NPPES (open it on the CMS NPI Registry). A record is not a license: verify it with the state board.
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Also registered at 5725 W Las Positas Blvd Ste 100

A shared address usually means a shared clinic or building; it does not show who employs whom.

  1. Sanna Daqiq, PA-CPhysician Assistant1730926858
  2. Shannon George, PA-CPhysician Assistant1487388823
  3. Ruby Maini, MDInternal Medicine Physician1063906063
  4. Sadaf Nagshbandi, PA-CPhysician Assistant1386398857

Verify John Gahagan in five checks

  1. 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
  2. 2LicenseActive license and public ordersMedical Board of California
    Search for license A126753
    Check the board
  3. 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
  4. 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
  5. 5CertificationBoard certificationABMS, AOA, NCCPA, AANPNot checked
Open the California license search

PlainDoctor does not match the HHS-OIG exclusion list to individual records: most entries carry no NPI. Search the OIG exclusion list by name.

Statewide context: the Medical Board of California reported 374 disciplinary actions in FY 2022-23. California discipline data →

74% fewer Medicare Part D claims than the average surgery physician in 2024

46 Medicare Part D claims for 37 beneficiaries, against an average of 174 among the 21,427 providers of this specialty who prescribed in Part D.

  1. John Gahagan46
  2. Specialty average174

Most prescribed

  1. Sod Sulf-Potass Sulf-Mag Sulf24 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.

One hospital or facility affiliation

  1. Stanford Health CareStanford, CA · Acute Care Hospitals5 of 5 stars

Source: CMS Doctors and Clinicians affiliations; Hospital General Information (Care Compare) (data.cms.gov). Star ratings are CMS hospital ratings, not ratings of this provider.

Surgery Physician providers in California

There are 3,381 surgery physician records in California.

Other surgery physician records in California

  1. Oliver Aalami, M.D.Stanford, CA1225229024
  2. Shahram Aarabi, MDOakland, CA1972700458
  3. Miriam Abaunza, M.D.Los Angeles, CA1538470778
  4. Benjamin Abbadessa, M.D.San Diego, CA1255593612
  5. Abdul-Rahman Abdel-ReheemLos Angeles, CA1831770437
  6. Sandy Abdelkedous, MDFresno, CA1306093109
  7. Hana Abdirahman, MDTemecula, CA1265288112
  8. Sherwin Abdoli, MDPetaluma, CA1508386442
  9. Michael Abdulian, MDGlendale, CA1649469628
  10. Mhdshafic Abdulkarim, MDOrange, CA1750174249

Common questions

What is John Gahagan, M.D.'s NPI number?

John Gahagan, M.D.'s National Provider Identifier (NPI) is 1558629493, issued on Apr 29, 2012. An NPI identifies a provider in billing; it is not a license.

Where is John Gahagan, M.D. located?

The NPPES record lists a practice address at 5725 W Las Positas Blvd Ste 100, Pleasanton, CA, 94588. Phone: (925) 734-8130. Providers update this record themselves, so call before visiting.

How can I verify John Gahagan, M.D.'s license?

NPPES lists California license number A126753, 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 John Gahagan, M.D. prescribe under Medicare Part D?

In 2024, John Gahagan, M.D. had 46 Medicare Part D claims for 37 beneficiaries; the average among surgery physician prescribers was 174. Part D covers Medicare prescriptions only.

Source: CMS National Plan and Provider Enumeration System (NPPES), loaded Aug 27, 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.

Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 27, 2026.