The abbreviations and titles that follow a healthcare professional’s name, known as post-nominal letters, often create confusion for the general public. These letters represent a hierarchy of educational achievement, professional licensure, and specialized certification. Understanding these designations is important for recognizing a provider’s qualifications and scope of practice. Deciphering combinations of letters like MD, PhD, FACS, or DPM helps comprehend the individual’s expertise and their role within the broader healthcare system.
The Purpose of Post-Nominal Letters
Post-nominal letters categorize an individual’s professional standing into three distinct areas: education, licensure, and professional achievement. The educational category includes degrees like MD or PhD, signifying the completion of an academic program. Licensure, sometimes represented by letters like RN (Registered Nurse), confirms the legal right to practice within a specific jurisdiction. Professional achievements represent a voluntary commitment to advanced standards beyond basic requirements.
This third category includes board certifications and fellowships in professional societies, indicating an elevated level of expertise or a peer-reviewed status. The combination of these credentials defines the practitioner’s authority, specialized knowledge, and limitations in practice.
Core Medical Degrees: Physicians and Surgeons
The most commonly recognized medical degrees in the United States are the Doctor of Medicine (MD) and the Doctor of Osteopathic Medicine (DO). Both MDs and DOs are fully licensed physicians who can practice in all medical specialties, prescribe medication, and perform surgery. Graduates from both programs complete four years of medical school followed by specialized residency training and often fellowship programs. Since 2020, the accreditation for graduate medical education has been unified, meaning MD and DO graduates compete for the same residency positions.
The primary difference lies in their foundational philosophical approach to patient care. MDs practice allopathic medicine, focusing on the diagnosis and treatment of disease using contemporary, evidence-based methods. DOs are trained in an osteopathic approach that emphasizes a holistic, “whole person” view, focusing on preventive care and the body’s innate ability to heal itself. DO students complete an additional 200 hours of training in Osteopathic Manipulative Treatment (OMT), a hands-on technique used to diagnose, treat, and prevent illness by manipulating the musculoskeletal system.
Other Primary Doctoral Degrees in Healthcare
A number of other doctoral degrees grant the right to use the title “Doctor” while operating in distinct clinical fields separate from general medicine. The Doctor of Dental Surgery (DDS) and the Doctor of Dental Medicine (DMD) are interchangeable degrees signifying a practitioner is a dentist. The distinction between DDS and DMD is purely administrative, as both require the same four years of education and clinical training.
Professionals specializing in the foot, ankle, and related structures of the leg earn the Doctor of Podiatric Medicine (DPM) degree. Podiatrists are licensed physicians and surgeons whose scope of practice includes diagnosing, treating, and performing surgery for conditions like bunions, fractures, and diabetic foot complications. The Doctor of Optometry (OD) is a primary care provider for the eye, trained to examine, diagnose, treat, and manage eye disorders, injuries, and diseases, and prescribe corrective lenses and certain medications. The Doctor of Veterinary Medicine (DVM) is the professional degree required for licensed veterinarians who specialize in the medical care of animals.
Academic and Research Doctoral Designations
The Doctor of Philosophy (PhD) is the most common academic doctorate, representing the highest level of scholarly achievement in a non-clinical field of study. Individuals with a PhD focus on conducting original research, generating new knowledge, and working in academic or research settings rather than providing direct patient care. While a PhD grants the right to use the title “Doctor,” it does not confer a license to practice clinical medicine or dentistry.
The Doctor of Psychology (PsyD) is a professional doctorate designed to train practitioners for clinical service, unlike the research-focused PhD in psychology. PsyD programs emphasize clinical practice, psychological assessment, and psychotherapy. The Doctor of Education (EdD) is another professional doctorate, typically focused on applying research to solve problems within educational systems and administration.
Professional Fellowships and Advanced Certifications
The letters following the primary degree often denote advanced professional status, board certification, or membership in a specialty organization. These designations are voluntary and require the practitioner to meet rigorous standards of competence and ethical conduct beyond initial licensing requirements. The letters FACS, or Fellow of the American College of Surgeons, indicate that a surgeon’s education, training, and professional conduct have been vetted and approved by a peer-review process, often requiring board certification in a surgical specialty.
FACP (Fellow of the American College of Physicians) and FAAP (Fellow of the American Academy of Pediatrics) are similar designations for internists and pediatricians, respectively, who have demonstrated professional excellence. Board certification is granted by medical specialty boards after a physician completes residency and passes comprehensive examinations. This voluntary certification signifies the physician possesses advanced expertise in a specific area, such as cardiology or neurosurgery.
Proper Ordering and Usage
The convention for listing multiple post-nominal credentials follows a standardized hierarchy. The highest earned academic or professional degree is listed first (e.g., MD, DO, DDS, or PhD). This degree is followed by any state-granted professional licenses, though the license is often implied by the primary degree and sometimes omitted.
The final items in the sequence are fellowships and certifications from professional societies, like FACS or FACP. A physician with a medical degree and a fellowship would list their credentials as “John Smith, MD, FACS.” This ordering provides a clear representation of the individual’s qualifications, moving from foundational education to specialized status. Verifying credentials can be done by checking with relevant state licensing boards and specialty certification organizations.