Dr. Issam A. Oneyssi, MD

Dr. Oneyssi practices at UMass Memorial Health - Harrington Hospital in Southbridge, Massachusetts, part of UMass Memorial Health Care.

Dr. Oneyssi's NPI, 1528026622, was assigned on May 1, 2006. Dr. Oneyssi holds Massachusetts license 76569.

Dr. Oneyssi's primary practice is UMass Memorial Health - Harrington Hospital, at 100 South Street, Southbridge, MA 01550 in Worcester County. The practice phone is (508) 765-9771.

Dr. Oneyssi's primary practice is UMass Memorial Health - Harrington Hospital in Southbridge, Massachusetts, part of UMass Memorial Health Care. The medical group on file is UMass Memorial Medical Group. Dmand AI also links Dr. Oneyssi to 1 more hospice and 1 medical group, each named with a free account.

Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Oneyssi practices, 2 sites in all. Vendor and product names are available with a free account.

Internal medicine is Dr. Oneyssi's primary specialty in the NPI Registry, under taxonomy code 207R00000X. Dr. Oneyssi is licensed in Massachusetts.

CMS data shows 494 Medicare services from Dr. Oneyssi across 5 procedure codes in 2024, for 176 Medicare patients. Medicare paid $47,161 for them. Every service was in a facility, such as a hospital, rather than an office.

CMS counts 176 Medicare patients who saw Dr. Oneyssi in 2024. The largest group is 65 to 74, with 59 patients. 75% of them have high blood pressure, and 75% have high cholesterol. 47% are also on Medicaid. Their average risk score is 2.46, where 1.00 is the Medicare average, so they are sicker than most Medicare patients.

Across all payers, Dmand AI patient panel data puts Dr. Oneyssi's median patient age at 70, with 49% women.

In 2024, Dr. Oneyssi wrote 268 Medicare Part D claims for 117 patients. 89% of them were for generic drugs. CMS names the drug for 74 of them, across 3 drugs with 11 or more claims each, at $1,269 in total drug cost. In 2023, CMS named 92 claims across 5 drugs.

Dr. Oneyssi accepts Medicare assignment, so Medicare's approved amount is taken as full payment.

CMS Open Payments shows 227 general payments to Dr. Oneyssi from 25 drug and device companies from 2016 to 2025. Food and beverage make up the largest share, 100% of the total. Pfizer Inc. paid the most, $973.