Doctor Who?
A comprehensive guide to understanding different types of doctors.
"Is there a doctor in the house?!"
Well, yes actually—there are two of us who co-host the Unbiased Science Podcast! One's a Doctor of Public Health (DrPH) and the other's a PhD in Neurobiology. Two very different flavors of doctor, but let's be honest: if someone on your flight starts having chest pains and the flight attendant asks "Is there a doctor on board?"... we're staying firmly in our seats.
That got us thinking: the title "doctor" and those letters after someone's name can mean a lot of different things. While they all signify advanced training and expertise, not all doctoral degrees are created equal—especially when it comes to dispensing health and medical advice. Some of us work in hospitals and clinics, others in labs, classrooms, or offices. Not all of us wear white coats (thank goodness), and our day-to-day work varies tremendously.
So whether you're curious about the physicians who might save your life mid-flight, or the scientists who could explain why the plane stays in the air in the first place, we've assembled a comprehensive guide to understanding different types of doctors, their education, licensing, and expertise. Did we miss any? Let us know and we'll update this guide!
Medical Doctors (MD/DO)
We’ll start with the most obvious types of doctors: physicians and surgeons. MDs (Medical Doctors) and DOs (Doctors of Osteopathic Medicine) are the classic diagnosticians, prescribing treatments and medications rooted in evidence-based medicine. Both of these degrees require 4 years of medical school and 3-7 years of residency, depending on specialization (e.g. family medicine, surgery, cardiology). Residency is sort of like an apprenticeship, during which recent medical school graduates train under the supervision of senior doctors, gaining hands-on, practical experience. MDs and DOs both must complete extensive licensing and board certification examinations in order to prescribe medication, perform surgeries, or to practice medicine in hospitals and clinics. Some, but not all, physicians choose to conduct clinical research as part of their careers; these “physician-scientists” are usually found in academic settings and play a vital role in clinical trials.
Dentists (DDS/DMD)
Dentists (Doctors of Dental Surgery/Medicine) are healthcare professionals specifically dedicated to the diagnosis, prevention, and treatment of conditions affecting the teeth, gums, mouth, and surrounding structures. Similar to medical school, dental school is a 4-year program that includes classroom learning and clinical practicum experience. Graduates must pass national and state-level exams to receive licensure and afterward are qualified to perform a variety of procedures including filling cavities, root canals, extractions, and placing crowns/dental implants.
Podiatrists (DPM)
Podiatrists (Doctor of Podiatric Medicine) specialize in diagnosing, treating, and preventing conditions related to the feet, ankles, and lower legs. Similar to medical and dental school, podiatric medical school is a 4-year program, but it is focused on both general medical education and specialized podiatric training. Following completion of the DPM degree, graduates complete a 3-year residency program for hands-on training in a clinical setting, which can include experience in podiatric surgery, radiology, and advanced orthotics, among others. To practice in the United States, podiatrists must pass a national licensing exam, in addition to some state-specific requirements.
Physical Therapist (DPT)
A physical therapist is a licensed healthcare professional who helps people restore or improve movement, manage pain, and prevent physical disabilities, often following injury. DPT degrees typically take 3 years to complete and include coursework in evidence-based techniques to promote healing, enhance mobility, and improve quality of life, often for patients with chronic conditions and illnesses. Part of their training involves clinical rotations in hospitals, rehab centers, and/or outpatient clinics to provide integral hands-on experience with patients in various settings. Graduates must pass a national licensing exam in order to practice in the United States, and physical therapists may choose to specialize in areas such as orthopedics, sports, and pediatrics. Importantly, though physical therapists are technically doctors, they typically prioritize patient clarity over formal titles in clinical practice so as to distinguish themselves from physicians.
Doctor of Nursing Practice (DNP)
DNP is a degree that prepares nurses for advanced clinical practice and leadership roles in healthcare, focused on translating research into practice. It is one of the highest levels of education a nurse can attain. Many DNPs advance to roles in clinical leadership, healthcare system improvement, and hospital administration. This degree typically takes 3-4 years of full-time study to complete, though part-time options are available as applicants are sometimes employed as registered nurses during their studies. DNP specializations cater to the broad spectrum of nursing specialties including nurse anesthetists, nurse practitioners, and nurse midwives. DNP-qualified nurses are required to obtain their Registered Nurse (RN) license and Advanced Practice Registered Nurse (APRN) license, which are granted by the state where the nurse plans to practice, though a DNP degree alone does not grant a license. Like physical therapists, DNPs may use the title "doctor" in appropriate contexts, though they clarify their role in clinical settings to avoid confusion with physicians.
Pharmacists (PharmD)
Pharmacists are highly trained healthcare workers who specialize in the preparation, dispensing, and proper use of medications. They are crucial in helping patients manage medications safely and effectively and work closely with physicians and surgeons to ensure proper medication compliance by patients. Pharmacy school is typically 4 years and includes advanced coursework in pharmacology (how drugs work), medicinal chemistry pharmaceutics (how drugs are made), and pharmacokinetics (how drugs move in the body). After earning their PharmD degrees, graduates must pass two licensing exams (one assessing knowledge of drug therapy and the other assessing pharmacy law), though exact requirements vary slightly by state. Although most pharmacists work in clinical settings, some work in research settings and contribute meaningfully to the development of new medications, therapies, and pharmaceutical technologies.
Clinical Psychologists (PsyD/PhD in Psychology)
Clinical psychologists are healthcare professionals who specialize in the diagnosis and treatment of emotional, mental, and behavioral disorders. They are trained to assess a wide range of psychological issues from stress/anxiety to more complex conditions such as personality disorders and schizophrenia. Clinical psychologists earn either a PsyD (Doctor of Psychology) or a PhD (Doctor of Philosophy) in clinical psychology, which typically take between 4-6 years to complete. Both degrees require the completion of an internship, a year-long period of supervised practice, prior to completing state-specific licensing exams. It is important to note that while psychologists are qualified to provide psychotherapy to patients (often called “talk therapy) using evidence-based techniques such as Cognitive Behavioral Therapy (CBT) or Dialectical Behavior Therapy (DBT), in most states they are typically not permitted to prescribe medication, although there are some exceptions.
Research Scientists (PhD)
A PhD (Doctor of Philosophy) is the highest degree awarded by universities and is designed to prepare individuals to conduct advanced, original research and contribute new knowledge to their field of study. The term “philosophy” in PhD historically refers to a love of wisdom/knowledge, but the degree is not limited to philosophy as a discipline and instead applies to a wide range of fields including the sciences, humanities, arts, and more. Crucially, a PhD focuses on conducting new research to address unanswered questions or challenges in a field. The degree typically takes 4-7 years to complete and involves designing and executing experiments, analyses, and/or studies under the mentorship of an advisory committee that provides expertise and feedback throughout the research process. PhD degrees culminate in the writing of a dissertation (or thesis) that serves as a comprehensive document presenting research findings, along with a defense of the dissertation before an expert committee.
Public Health Scientists (DrPH)
A DrPH (Doctor of Public Health) is a professional degree designed to prepare individuals for leadership roles in public health practice and policy. Unlike a research-focused degree like a PhD, the DrPH centers on solving practical problems in public health and emphasizes leadership, management, and evidence-based solutions to improve health systems and population health. These types of programs typically take 3-5 years to complete (following completion of a Master’s degree in public health, which is a pre-requisite for most programs) and focus on an applied project that addresses a pressing public health challenge rather than purely theoretical research.
Optometrists (OD)
Optometrists (Doctors of Optometry) are primary healthcare professionals who specialize in eye and vision care, including diagnosing and treating various eye conditions, prescribing corrective lenses, and managing diseases like glaucoma and cataracts. The OD degree typically requires 4 years of optometry school following undergraduate studies, combining classroom instruction with clinical training. The curriculum covers anatomy, physiology, optics, vision science, and the diagnosis/treatment of eye diseases. After graduation, optometrists must pass national board examinations and meet state-specific licensing requirements to practice. While optometrists can prescribe certain medications for eye conditions, perform vision therapy, and provide pre/post-operative care, they are distinct from ophthalmologists (MDs who specialize in eye surgery and treatment of complex eye diseases).
Veterinarians (DVM)
Veterinarians (Doctors of Veterinary Medicine) are medical professionals dedicated to animal health, providing care for pets, livestock, and wildlife. Earning a DVM requires completion of a 4-year veterinary medicine program that includes both classroom learning and extensive clinical rotations. The curriculum covers animal anatomy, physiology, disease prevention, surgery, and species-specific medicine. Like human medicine, some veterinarians choose to specialize in specific areas such as surgery, internal medicine, or emergency care through additional residency training. To practice, DVMs must pass the North American Veterinary Licensing Examination and meet state-specific requirements. Veterinarians are qualified to diagnose illness, perform surgery, prescribe medications, and provide preventive care for animals, making them essential healthcare providers for both companion animals and livestock.
Audiologists (AuD)
Audiologists (Doctors of Audiology) are healthcare professionals who specialize in the prevention, diagnosis, and treatment of hearing, balance, and other auditory disorders. The AuD program typically takes 4 years to complete and includes coursework in anatomy, physiology, physics of sound, hearing devices, and diagnostic techniques. Students complete supervised clinical practice in various settings, working with patients across the lifespan. After earning their degree, audiologists must pass a national examination and obtain state licensure to practice. They are qualified to conduct hearing tests, fit hearing aids, provide vestibular (balance) therapy, and work with cochlear implant patients. While audiologists often work in medical settings alongside physicians, they focus specifically on hearing and balance-related healthcare, distinguishing them from ENT (ear, nose, and throat) physicians who provide broader medical care.
Alternative/Complimentary Medicine Doctors
Several doctorate degrees offer training in health/wellness treatments outside of conventional, evidence-based science and medicine approaches. These training programs are often non-standardized and emphasize holistic care, natural remedies, and non-invasive approaches to healing. For example, a Doctor of Naturopathic Medicine (ND) focuses on holistic health using natural remedies such as herbal medicine, acupuncture, and lifestyle counseling, while a Doctor of Chiropractic Medicine (DC) focuses on non-invasive treatment of the spine, bones, and joints. Additionally, practitioners of functional and integrative medicine will also often refer to themselves as doctors. These types of doctors should not be confused with physicians as they are not authorized to prescribe medication, do not attend medical school, and frequently promote treatments that are not evidence-based. In other words, there is often insufficient clinical evidence to support many of the claims made by practitioners of alternative/complementary medicine.
So, whenever you come across an Instagram reel or YouTube video where someone introduces themselves as a “doctor,” make sure to click over to their bio and pay attention to the letters after their name. Be wary of NDs and DCs masquerading as medical doctors, and keep in mind that no matter what, all doctors are humans who are susceptible to occasional errors in judgment and cognitive biases. It is essential to critically evaluate their advice, verify their credentials, and consult multiple reputable sources when it comes to your health. In a world of misinformation and anecdotal claims, relying on evidence-based practices and expert consensus is key to making informed decisions.
Stay curious,
Unbiased Science