Finish a bachelor's degree, if you haven't already as part of your nursing degree. The usual recommended degree is a Bachelor of Science in Biology, which will eliminate many of the prerequisites you may need as part of medical school.
Apply for medical school. Make sure that your school is accredited by the Liaison Committee on Medical Education, which is important if you wish to practice medicine in the United States.
Complete a residency under the supervision of a senior physician. Residencies last three to seven years, depending on the program. A residency in pediatrics lasts three years, whereas a surgical residency program typically takes five years to complete.
Complete a fellowship if you would like to specialize further, such as in adolescent psychiatry or gastroenterology. A fellowship lasts one to three years and will prepares you to practice medicine in your specialization.
Take your licensing exams for the state and specialty you wish to practice in. This license will allow you to practice medicine independently. You may also wish to become board certified, which tells patients that you have passed very thorough and specific tests in your specialization.