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License & Identifications

A medical license is required for a doctor to practice medicine in a particular state. Requirements vary by state but most require, at a minimum, post-graduate training in the doctor’s specific specialty. An NPI number is a national identifier unique to an individual health care provider and is managed by the Center for Medicare & Medicaid Services (CMS).

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Specialties & Research

Dr. Karen O'Brien, MD is board certified in Internal Medicine.

  • She has special expertise in 2 areas:
  • Hot Flashes
  • Menopause

Education & Awards

Dr. O'Brien graduated from Brown University, Providence.


Dr. O'Brien has 5 hospital affiliations:

  • Massachusetts General Hospital 
  • Tufts Medical Center Hospital 


  • Spanish

> > > > Dr. Karen O'Brien, MD

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Additional Information
Dr. Karen Anne O'Brien MD is a female Internist, has 22 years of experience and practices in Internal Medicine.
Where does Dr. Karen A. O'Brien practice?
Dr. Karen O'Brien has 3 office locations.
Dr. Karen O'Brien practices Internal Medicine near Chelsea, MA.
Additional practice locations include: Boston, MA.
See Chelsea Internists.