Nick J. Karahalios, MD
NPI 1255442505ActiveIndividual· Internal Medicine· San Clemente, CA
Internal Medicine (MD) in San Clemente, California, trained at Un of California, Irvine, College of Medicine (class of 1992). Their prescriptions cost Medicare Part D more than their services did: $178,683 for 1,910 claims, against $108,394 paid for services in 2024. Exact Sciences Corporation reported $17.52 in payments in 2025, mostly food and beverage.
Overview
| NPI | 1255442505 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD |
| Sole proprietor | No |
| NPI issued | Aug 31, 2006 |
| Last updated in NPPES | May 27, 2021 |
| Certified by provider | May 27, 2021 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine Primary | 207R00000X | G77834 | CA |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Nov 10, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 11, 2026 | No match | — |
| New York OMIG · Nov 11, 2026 | No match | — |
| Ohio Medicaid · Nov 11, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 11, 2026 | No match | — |
| Washington HCA · Nov 11, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Internal Medicine (CA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 104 |
|---|---|
| Services billed | 1,575 across 47 procedure codes |
| Paid by Medicare | $108,394 |
Part D prescriptions in 2024
| Prescriptions (claims) | 1,910 · 3,539 30-day fills |
|---|---|
| Patients | 108 |
| Total drug cost | $178,683 |
| Generic share | 88% of claims |
Education and affiliations
| Medical school | Un of California, Irvine, College of Medicine |
|---|---|
| Graduation year | 1992 |
| Medicare specialty | Internal Medicine |
| Telehealth | Offers telehealth |
Medical group
- San Clemente Internal Medical Group IncSan Clemente, CA · 2 clinicians
Hospital affiliations
- Memorialcare Saddleback Medical CenterLaguna Hills, CA
- Providence Mission HospitalMission Viejo, CA
Other facilities
- Acacia Hh&p of Southern California, LLCHome health agency · Irvine, CA
- Acacia Home Health ServicesHome health agency · Glendale, CA
- Acacia Hospice and Palliative ServicesHospice · Irvine, CA
- San Juan Hills Healthcare CenterNursing home · San Juan Capistrano, CA
Industry payments (Open Payments)
- 2025$17.52 · 1 payment from 1 company
- 2024$52.95 · 3 payments from 1 company
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Exact Sciences Corporation | $17.52 | 1 |
What the 2025 payments were for
- Food and Beverage$17.52 · 1 payment
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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All 27 internal medicine physicians in San Clemente · All internal medicine physicians in California