How many years do you have to be in medical school a nurse?

There's a misunderstanding in the question. Medical school is for becoming a doctor (physician), not a nurse. Nurses follow a different educational path.

The length of education for nurses varies:

* Associate Degree in Nursing (ADN): Typically takes 2 years.

* Bachelor of Science in Nursing (BSN): Typically takes 4 years.

There is no medical school involved in becoming a nurse.