Mark Hreish
Psychiatry Physician · Riverside, CA
Mark Hreish is a psychiatry physician with a practice address in Riverside, California, and NPI 1164839502, issued on Jul 17, 2014. Check the license (California A137381, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Mark Hreish
- Primary taxonomy
- Psychiatry Physician 2084P0800X
- License number
- A137381 CA
Self-reported in NPPES; status is on the state search - Practice location
- 10800 Magnolia Ave, Riverside, CA 92505
- Phone
- (951) 353-2000
- Enumerated
- Jul 17, 2014
- Record last updated
- Dec 1, 2021 (not updated in 5 years: call before relying on the address or phone)
- Medicare enrollment
- Enrolled (PECOS I20160922000643); accepts Medicare assignment
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest psychiatry physician records → All 8,673 in California → Look up another NPI →
Also registered at 10800 Magnolia Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Mark Hreish in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A137381Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
43% more Medicare Part D claims than the average psychiatry physician in 2024
1,434 Medicare Part D claims for 226 beneficiaries, against an average of 1,000 among the 35,054 providers of this specialty who prescribed in Part D. Brand-name drugs were 5% of claims.
Most prescribed
- Buspirone Hcl213 claims
- Trazodone Hcl162 claims
- Sertraline Hcl107 claims
- Quetiapine Fumarate97 claims
- Fluoxetine Hcl80 claims
- Bupropion Xl60 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 GroupRiverside, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Mark Hreish among 8,673 psychiatry physician records in California
Mark Hreish 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 2014, is newer than 71% of them.
- NPI issued2014 · 71% of these records are older, 26% newer
- In a Medicare fileYes · 67% of these records are
- In the CMS Doctors and Clinicians fileYes · 38% of these records are
- Graduated2012 · median 2005 among the 3,295 with a school on file
- Record last updated2021 · 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).
134 psychiatry physician records list a practice address in Riverside
They are 134 of the 13,893 NPPES records with a practice address in Riverside, and 8,673 psychiatry physician records in California.
All 8,673 in California → Every provider in Riverside → Psychiatry Physician nationwide →
The 8 psychiatry physician records with the nearest ZIP codes
- Lilian Caylan, MDRiverside, CA 925051871660696
- Daniel Hackett, MDRiverside, CA 925051982775961
- Quiana JohnsonRiverside, CA 925051104745413
- Naga Kothapalli, MDRiverside, CA 925051619301579
- David Scarpino, MDRiverside, CA 925051548251192
- Evan Tzakis, MDRiverside, CA 925051609943422
- Maria Villarosa, MDRiverside, CA 925051861540759
- Joanne Wyszomirski-Witkowski, MDRiverside, CA 925051962579813
Common questions
What is Mark Hreish's NPI number?
Mark Hreish's National Provider Identifier (NPI) is 1164839502, issued on Jul 17, 2014. An NPI identifies a provider in billing; it is not a license.
Where is Mark Hreish located?
The NPPES record lists a practice address at 10800 Magnolia Ave, Riverside, CA, 92505. Phone: (951) 353-2000. Providers update this record themselves, so call before visiting.
How can I verify Mark Hreish's license?
NPPES lists California license number A137381, 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 Mark Hreish prescribe under Medicare Part D?
In 2024, Mark Hreish had 1,434 Medicare Part D claims for 226 beneficiaries; the average among psychiatry physician prescribers was 1,000. 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.