MDs and DOs: Who Can Be a Doctor in California?
Understanding Physician Licenses and the Difference Between MDs and DOs
You might notice that some doctors have “MD” after their names, while others have “DO.” What do those letters mean, and how does it affect the care you receive?
We’ll break down the different types of physician licenses in California, the difference between MDs and DOs, and what it all means for you as a patient.
What can licensed physicians do?
In California, doctors must be licensed by the state in order to practice medicine. This license proves they’ve completed years of medical school, hands-on training, and passed rigorous exams.
There are two types of licensed physicians in California:
- MDs (Doctors of Medicine): licensed by the Medical Board of California
- DOs (Doctors of Osteopathic Medicine): licensed by the Osteopathic Medical Board of California
Both MDs and DOs are fully trained physicians who can:
- Diagnose and treat illnesses
- Prescribe medications
- Perform surgery
- Provide preventive care
MD vs. DO: What’s the difference?
While both types of doctors are licensed to provide the same care, they come from slightly different medical traditions.
| MD (Doctor of Medicine) | DO (Doctor of Osteopathic Medicine) |
|---|---|
| Traditional medical school approach (also called allopathic medicine) | A holistic medical philosophy called osteopathic medicine |
| Focuses on treating symptoms and diseases | Emphasizes treating the whole person, including lifestyle and prevention |
| Trained in medicine, surgery, and pharmaceuticals | Trained in medicine, surgery, and pharmaceuticals, plus hands-on bodywork (OMT) |
| Most commonly seen in the U.S. and internationally | Growing rapidly in the U.S., especially in primary care |
Most patients don’t notice a difference in practice, because there often isn’t one. MDs and DOs work side by side in hospitals and clinics, complete the same residencies, and take the same licensing exams (with a few differences early on).
What levels of licenses can a doctor have in California?
For both MDs and DOs, depending on where a doctor is in their career, they might hold a different type of license. Here’s what that can look like:
1. Postgraduate Training License (PTL)
Who it’s for: Doctors (MDs and DOs) in residency (hospital training after med school).
What it means for you: These doctors are still in training and work under supervision. You’ll often see them in teaching hospitals.
2. Full Physician License (Physician’s and Surgeon’s License)
Who it’s for: the full Physician’s and Surgeon’s License (P&S license) is for fully trained MDs and DOs who have completed at least 3 years of residency. Note that this is not just for surgeons – physicians may be called surgeons regardless of whether they actually practice surgery.
What it means for you: These doctors are qualified to practice on their own, diagnose, treat, and manage your care independently.
3. Special Permits or Limited Licenses
Who it’s for: Doctors from other countries or researchers who aren’t seeing patients independently. See more at Medical Board of California website.
What it means for you: These doctors may work behind the scenes or in supervised roles.
4. Volunteer License
Who it’s for: Retired doctors who want to give back by working in free clinics or nonprofits
What it means for you: You may see these experienced doctors providing care in underserved communities.
What does “Board-Certified” mean?
Being board-certified means a doctor has gone beyond basic licensing by passing additional exams in a medical specialty (like cardiology, family medicine, or psychiatry). It shows they’ve met national standards and stay current through ongoing education. While board certification is not required to practice medicine, it is a mark of advanced expertise.
You can check a doctor’s certification status at CertificationMatters.org.
How to check a doctor’s license?
If you want to know whether a doctor is licensed and in good standing, you can search their credentials online:
- MDs: Medical Board of California License Lookup
- DOs: Osteopathic Medical Board of California License Lookup
These databases let you see whether a doctor is actively licensed, where they went to medical school, and whether they’ve had any disciplinary actions.
What is a naturopathic doctor?
Naturopathic doctors focus on herbal medicine and lifestyle factors, and have a more limited scope of practice than MDs and DOs. See our Guide to Naturopathic Doctors (NDs).
Further Resources
Guide to Laws about Healthcare
Guide to Naturopathic Doctors (NDs)
Guide to Complementary and Alternative Medicine
Image credit: by prostooleh on Freepik
