Gemma Guillermo, M.D.
Psychiatry Physician · Redwood City, CA
Gemma Guillermo, M.D. is a psychiatry physician with a practice address in Redwood City, California, and NPI 1831154418, issued on Apr 18, 2006. Check the license (California 61066, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Gemma Guillermo
- Credential
- M.D.
- Primary taxonomy
- Psychiatry Physician 2084P0800X
- License number
- 61066 CA
Self-reported in NPPES; status is on the state search - Practice location
- 170 Alameda DE Las Pulgas, Redwood City, CA 94062
- Phone
- (650) 367-5559
- Enumerated
- Apr 18, 2006
- Record last updated
- Feb 13, 2019 (not updated in 7 years: call before relying on the address or phone)
- Fax
- (650) 368-3754
- Medicaid ID
- 3967836 CA
- Medicare enrollment
- Enrolled (PECOS I20041108000434); accepts Medicare assignment
- Medical or professional school
- Js Weill Medical College, Cornell University, 1995
- Entity
- Type 1 · individual
8 nearest psychiatry physician records → All 8,673 in California → Look up another NPI →
Also registered at 170 Alameda DE Las Pulgas
A shared address usually means a shared clinic or building; it does not show who employs whom.
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- Jyothi Adsumilli, M.D.,Hospitalist Physician1245508159
- Ari AuwinitzkyPerfusionist1629585583
- Marjorie Berry Simon, LCSWClinical Social Worker1639477532
Verify Gemma Guillermo in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license 61066Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
90% fewer Medicare Part D claims than the average psychiatry physician in 2024
98 Medicare Part D claims for 23 beneficiaries, against an average of 1,000 among the 35,054 providers of this specialty who prescribed in Part D. Brand-name drugs were 14% of claims.
Most prescribed
- Hydroxyzine Hcl14 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.
The practice group's MIPS final score for 2023 (Medicare payment program): 80.6 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023, group reporting; category weights for 2023 (qpp.cms.gov).
Industry payments in 2024: $475.84
4 payments; by number, the most common kind was food and beverage; the largest payer was Teva Pharmaceuticals USA, Inc. The 13,693 providers of this specialty with any payment received $4,954.93 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through one group practice
- County OF Santa ClaraSan Jose, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Gemma Guillermo among 8,673 psychiatry physician records in California
Gemma Guillermo, M.D. is one of 8,673 psychiatry physician records with a practice address in California. 67% 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 2% of them.
- NPI issued2006 · 2% of these records are older, 67% newer
- In a Medicare fileYes · 67% of these records are
- In the CMS Doctors and Clinicians fileYes · 38% of these records are
- Graduated1995 · median 2005 among the 3,295 with a school on file
- Record last updated2019 · 54% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 2084P0800X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Psychiatry Physician providers in California
There are 8,673 psychiatry physician records in California.
All 8,673 in California → Every provider in Redwood City → Psychiatry Physician nationwide →
The 8 psychiatry physician records with the nearest ZIP codes
- Frank Adair, M.D.Redwood City, CA 940621043242381
- Alan Brauer, M.D.Redwood City, CA 940621972693307
- Ronald Seff, M.D.Woodside, CA 940621891792925
- Norman Weinstein, M.D.Woodside, CA 940621194968032
- Joris Wiggers, M.D.Redwood City, CA 940621104994037
- Anil Assudani, M.D,Redwood City, CA 940631497753909
- Sarah Carey, MDRedwood City, CA 940631164509345
- John Furman, M.D.Redwood City, CA 940631639251697
Common questions
What is Gemma Guillermo, M.D.'s NPI number?
Gemma Guillermo, M.D.'s National Provider Identifier (NPI) is 1831154418, issued on Apr 18, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Gemma Guillermo, M.D. located?
The NPPES record lists a practice address at 170 Alameda DE Las Pulgas, Redwood City, CA, 94062. Phone: (650) 367-5559. Providers update this record themselves, so call before visiting.
How can I verify Gemma Guillermo, M.D.'s license?
NPPES lists California license number 61066, 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 Gemma Guillermo, M.D. prescribe under Medicare Part D?
In 2024, Gemma Guillermo, M.D. had 98 Medicare Part D claims for 23 beneficiaries; the average among psychiatry physician prescribers was 1,000. Part D covers Medicare prescriptions only.
What is Gemma Guillermo, M.D.'s MIPS final score?
The 2023 MIPS final score is 80.6 of 100, reported for the practice group. The average among 454,083 clinicians with a measured score was 83.5.
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.