Mallory Katherine Willenborg, PA-C
Emergency Medicine Physician · Colton, CA
Mallory Katherine Willenborg, PA-C is an emergency medicine physician with a practice address in Colton, California, and NPI 1598213886, issued on Sep 14, 2016. Check the license (California 53867, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Mallory Katherine Willenborg
- Credential
- PA-C
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License numbers
- 53867 CA
9109799 FL
Self-reported in NPPES; status is on the state search - Practice location
- 400 N Pepper Ave, Colton, CA 92324
- Phone
- (909) 580-1000
- Enumerated
- Sep 14, 2016
- Record last updated
- Dec 10, 2016 (not updated in 10 years: call before relying on the address or phone)
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 7,751 in California → Look up another NPI →
Also registered at 400 N Pepper Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Shangrila AbaricoRegistered Nurse1609659325
- Susana AbaroRegistered Nurse1114425162
- Patricia AbbaRegistered Nurse1013188838
- Mohammad Hossein Abbasi, MD, MPHStudent in an Organized Health Care Education/Training Program1609622166
- Ala AbedrabboCertified Registered Nurse Anesthetist1972333144
- Mary AboagyeLicensed Vocational Nurse1982875605
Verify Mallory Katherine Willenborg in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license 53867Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
50% fewer Medicare Part D claims than the average emergency medicine physician in 2024
114 Medicare Part D claims for 77 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D. 22 claims were for opioids.
Most prescribed
- Cephalexin19 claims
- Hydrocodone-Acetaminophen15 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.
Mallory Katherine Willenborg among 7,751 emergency medicine physician records in California
Mallory Katherine Willenborg, PA-C is one of 7,751 emergency medicine physician records with a practice address in California. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2016, is newer than 75% of them.
- NPI issued2016 · 75% of these records are older, 22% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileNo · 59% of these records are
- Record last updated2016 · 59% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207P00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
110 emergency medicine physician records list a practice address in Colton
They are 110 of the 2,459 NPPES records with a practice address in Colton, and 7,751 emergency medicine physician records in California.
All 7,751 in California → Every provider in Colton → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- Rodney Borger, M.DColton, CA 923241619917465
- Richard Hausman, D.O.Colton, CA 923241922049113
- Ali Jamehdor, D.OColton, CA 923241528009008
- Robert Kollen, M.DColton, CA 923241073554531
- Eugene Kwong, M.DColton, CA 923241003857020
- Carol Lee, M.DColton, CA 923241043251143
- Pamela Lux, D.OColton, CA 923241427090323
- Thomas Minahan, D.OColton, CA 923241457394827
Common questions
What is Mallory Katherine Willenborg, PA-C's NPI number?
Mallory Katherine Willenborg, PA-C's National Provider Identifier (NPI) is 1598213886, issued on Sep 14, 2016. An NPI identifies a provider in billing; it is not a license.
Where is Mallory Katherine Willenborg, PA-C located?
The NPPES record lists a practice address at 400 N Pepper Ave, Colton, CA, 92324. Phone: (909) 580-1000. Providers update this record themselves, so call before visiting.
How can I verify Mallory Katherine Willenborg, PA-C's license?
NPPES lists California license number 53867, 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 Mallory Katherine Willenborg, PA-C prescribe under Medicare Part D?
In 2024, Mallory Katherine Willenborg, PA-C had 114 Medicare Part D claims for 77 beneficiaries; the average among emergency medicine physician prescribers was 226. 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.