JOHN MCMAHON, DO appears in the CMS NPPES registry as a Sports Medicine (Internal Medicine) Physician provider holding DO credentials at 1900 LAFAYETTE RD, PORTSMOUTH, NH, 03801, with a listed phone of (603) 431-1121. NPI 1821258062 was issued on 06/11/2008. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what MCMAHON most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 85 prescription claims written by this provider, covering 46 Medicare beneficiaries and totaling roughly $851 in drug spend, with an opioid prescribing rate of 34.1%. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy. On the CMS Merit-based Incentive Payment System, this provider earned a Final Score of 77.6308/100 for the 2023 performance year, compared with the national average of 83.1.

Sports Medicine (Internal Medicine) Physician is a narrow specialty nationwide, with 292 enrolled providers across 43 states and an average of 1,267 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline. Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist — always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.