The length of time it takes to become a doctor when you already have a nursing degree is variable. It depends on what kind of degree you have and whether you want to become a medical doctor or earn a nursing doctorate. The two degrees are different and have different requirements. Many factors affect how long you will be in school.

Your Initial Education

In many professions, your educational path is relatively simple: you go to college and begin your career. In nursing, however, your first choice is whether you want to earn an associate degree, a nursing diploma or a baccalaureate in nursing, usually referred to as a BSN. An associate degree usually takes two years, although you may need an additional year to complete prerequisites. A nursing diploma, which is offered through some schools of nursing, takes two to three years depending on the program. A BSN takes four years. All of these allow you to sit for the NCLEX-RN national licensing exam.

Transfer or Start Over

Your initial choice of education affects your choices in going on to become a physician or doctorally prepared nurse. Not all diploma and associate courses are transferable credits. You may need to start over again and obtain a bachelor’s degree, either in nursing or in another science. If you want to pursue medical school, either a BSN or a baccalaureate in any subject with a concentration of science should be sufficient. The nursing doctorate, however, is more likely to require a BSN.

Medical School or a Master's

Once you have a bachelor’s degree, you’ll spend another four years in medical school or at least two more years getting a master’s degree in nursing. Following medical school, you go on for a residency of three to five years – the length depends on the specialty you choose. Some physicians also choose fellowship training, an extended period of specialty education. For a nursing doctorate, you would apply to a doctorate program after you finish your master’s. Expect to spend three to five years getting your doctorate.

Completing Your Education

The exact length of time your education will take depends on several variables. If you started your nursing career with a diploma and had to go back to school for your BSN, it could take an additional eight years to complete your doctorate. Some BSN to Ph.D. programs take only five years, according to a September 2009 article on the AllNurses.com website. Seven years is the minimum time from entry to medical school to completion of residency; again, the total time will be affected by your initial nursing degree or diploma. A nurse who must work while completing her education might take longer than a nurse who is able to go to school full-time.